Dororo was shaking while he thought about what he would do, though he couldn’t tell for sure if it was anxiety making him shake or if it was shame. He wanted least of all for it to be anticipation. But while he thought of his bound former superior officer, he had trouble pretending he was feeling anything else. His quivering only increased as he tried to deny it, but an unrelenting stiffness both in and between his legs made it undeniable. 
       
       “Um… Dororo…” The blue frog rushed to cover himself at the sound of his friend’s voice, though he wasn’t sure why. After all, this was what he had wanted, right? “Help a frog out? I’m kinda tied up here, kero-kero.”
       
       The sound of that laugh sent Dororo spiraling backwards, to a time almost forgotten. The laughter then had shaken him to his very core. He remembered it had started so innocently, with his best friend coming over to visit, even though he knew something was wrong when Keroro had rushed him to his room first thing. 
       
       “I found a naughty magazine!” It was the first thing Keroro said. He hadn’t even bothered to say hi before dragging Dororo onto the bed, and the little blue frog hadn’t even questioned him the whole journey to the mattress. “You wanna see!? I need somewhere to hide it from my dad.”
       
       Dororo at the time had no idea how to respond. He just stuttered aimlessly about how it was bad or maybe that they weren’t supposed to for some reason. Keroro didn’t listen of course. He’d already gotten the magazine open whilethe little blue frog had been covering his eyes. 
       
       He didn’t remember exactly what had been in the magazine. However, he knew that it must have been depictions of oral sex, because the next memory he had was a clear picture of his best friend’s crotch, and a slimy pink appendage peeking out from it. The next memory was of the weight of a hand on the back of his head and someone pulling at the mask he always wore. 
       
       “Come on, Zeroro! Get that mask off so you can give it a try!” Keroro had sounded playful, but the blue frog knew it was an order. Still it was one he resisted, forcing his friend to pull and push harder. “The girls in the picture really liked it, I bet you will too.”
       
       Dororo had been shaking that time too, though in that case he knew where it came from. His anxiety had been overwhelming. The idea of touching something so dirty with his precious mouth had absolutely terrified him. “K-Keroro, I d-don’t…”
       
       “Do it and you’ll be my best friend!” The phrase stopped Dororo’s shivering for a moment, but the haunting laugh had brought it right back, just in time for Keroro to finally snap the back of his mask and push the blue frog’s face against his slimy, pink dick. “Kero-kero… Giroro wouldn’t try it… he’s such a lame-o.”
       
       Spurred on by the idea of not just keeping his friend but earning the cherished title of ‘best friend’, the blue child had foolishly gone along with Keroro’s wishes. He wouldn’t have been able to fight against Keroro’s pushing anyway, but he didn’t even think about fighting. He was still shivering when he opened his mouth and put Keroro’s dick in it though, and he continued to shiver even more once it was in. 
       
       It tasted dirty, slimy, wet, and sour. The taste was bad enough to make him almost spit it out, but he persevered for friendship’s sake even as the sour taste slowly became saltier and saltier with the introduction of a new slime. At that age, he was sure everything about the action would make him violently ill, maybe even kill him, but he needed to be Keroro’s best friend. He would give up his life for that. 
       
       And at the time it had seemed worth it too. Sure, the idea of sickness made tears stream down his face, but the praise he got from his friend had convinced him those were tears of joy. “Wowee! That feels amazing, you are the best friend, Zeroro!”
       
       After that though, things got so much worse. 
       
       Dororo’s mind quickly jumped to the next time he’d heard that horrific laughter. “Kerokero… Come on, Zeroro, you’re acting like you’re not my friend.” Dororo remembered being pinned underneath his friend and kicking at him, but nothing could get Keroro off him. The look in his face was clear as day. It was almost demonic, totally overcome with lust. He licked his lips when he laughed again. “I bet it doesn’t even hurt.”
       
       The slimy appendage between Keroro’s legs had been poking at his tail the whole time. In fact, Dororo knew now that the frog had doubtlessly been trying to get inside him with every poke, he was just too clumsy to hit the mark with how much the young blue frog had kicked at him. 
       
       “N-no! K-Keroro…” He remembered pleading with his friend. That this had been a step too far. Even with his own little blue body betraying him and showing off his own erection, he was still far too panicked to consent. 
       
       But Keroro had gone ahead anyway, silencing little Zeroro with a kiss and sending him into a muffled scream when he finally hit the mark above his victim’s tail.
       
       The memory of that kiss faded with a blink of his eyes, and Dororo suddenly found himself in the position of power, standing above a prone Keroro with his flippers pinned to the ground by a booby trap. He wasn’t sure when he’d gotten there, but he knew in his heart why he was there. Based on the frightened look on his face, Keroro knew what they were doing there too.
       
       “D-Dororo, hey, buddy! Wh-what’s going on?” Keroro tried to smile and look in his friend’s eyes, but they continuously darted towards Dororo’s groin. The unrelenting stiffness had totally overtaken him at this point, evidently leaving his legs and going straight to his erection. Now, the blue frog was fully hard, and since his hands were resting on either side of Keroro’s head, he wasn’t hiding it anymore.
       
       “K-Keroro…” Dororo considered what he wanted. Here Keroro was, at his mercy. His childhood tormentor… and his best friend. Tears started to fill his eyes as his cock ached relentlessly. “Y-you…” He couldn’t find the words or the strength to continue for a moment. His knees even buckled, bringing his face closer to the green frog’s. It also pressed his rigid cock against Keroro’s groin, the throbbing that came from it gave him the strength to continue. “Y-you jerk!”
       
       Keroro seemed stunned at first, almost hurt. That didn’t last though, as the look of terror came back quickly once Dororo’s hands wrapped around his legs and spread them apart. “D-Dororo… I get that I’m a prime example of frog, but usually I like a little foreplay, y’know.” He tried to speak casually still, but a quavering in his voice betrayed an intense fear, or maybe an arousal. After all, in spite of his complaining Dororo knew that the green frog was getting turned on. He was blushing behind the fear, and there was just the smallest hint of an erection between his spreading legs. “M-maybe if we start with a little kissing?”
       
       “You jerk… You don’t even remember, do you?” Dororo was shaking again. He remembered the feeling of Keroro’s pounding, how much it had hurt the first time. He remembered how he had cried for him to stop. However, the shaking was brought on by memories of the pleasure he had felt. He remembered Keroro’s scrunched up face when he’d cum inside him, and he remembered how his own body had quaked when it was wracked by his first orgasm. 
       
       He didn’t remember if he even came properly, as young as he was. He just remembered feeling so overwhelmed that he was scared he was having a heart attack. It barely registered as pleasure at the time. However, there was something about it he couldn’t help but enjoy, something that quieted his fear for just a moment. And, it had given him the energy to finally cry out loudly enough to get his friends attention. 
       
       At least, that was how he wanted to remember it. When he usually thought back to the scene his next memory was being alone as Keroro slammed the door and shouted goodbye. Everything felt wet, and he was still crying hard enough he was sure he just missed the apology. But now, with Keroro bound and waiting for him, new memories flooded him: memories of Keroro continuing his pounding, shouting his old name, and cumming inside of him. Then, the memory of Keroro leaving as if they’d just casually shared a comic book, barely even registering his tearful friend. 
       
       Dororo’s dick was pulsating as he thought of that. His head filled with shame and anger that both kept him still and forced him to move. Eventually the anger would win out. “Let me show you then.” He spoke almost gently as he aligned himself with his friend’s rear. He wanted Keroro to feel what he went through. Every bit of it.
       
       So, the blue frog thrust in hard, just like his friend had when they were young. There wasn’t an ounce of grace or kindness. There was just a violent need. And Keroro cried out. At first it was unintelligible, but then the words came together. “Z-Zeroro… st-stop!” Dororo watched as his face jumped rapidly between shock and pain. One moment his eyes would be wide open and in another his whole face would scrunch up in a face almost identical to his orgasm. Dororo knew in his heart he was feeling pleasure, even when he screamed. “Stop! Stop! K-Kerooooo!”
       
       As if to reassure the blue frog, his friend’s dick bounced against his belly with every one of Dororo’s powerful thrusts. The floor underneath them shook too with how strong Dororo’s anger was. Most importantly though, Keroro himself was quaking around his dick, and it felt heavenly. It was like sticking it into a vibrating fleshlight, one that gripped his dick like a vice. “W-was this what you loved so much, Keroro…” He couldn’t help but groan as he thought back to his own quaking body as a child. There was no doubt in his mind that Keroro had enjoyed it just as much as he did now.
       
       “N-No! Zeroro!” Keroro was starting to whimper now as his voice lost strength and his eyes slammed shut. Dororo felt him start to kick at his hips while his ass continued to squeeze and pull against its intruder. “I d-don’t- Kero!” He tried to keep talking, but every new thrust silenced him again. Eventually he was reduced to simply whimpering an incoherent “Kero,” at every reentry. Tears even started to drip from the corners of his tightly squeezed eyes.
       
       That was when Dororo leaned down and kissed him, muffling those whimpers and swallowing Keroro’s desperate breaths. That was why Keroro had kissed him before for sure, to feel that warmth. It was intoxicating. Nearly overwhelming. In truth Dororo wanted desperately to keep it going and had to hold himself back. He could have cum right there, especially when Keroro’s whole body spasmed and he felt the green frog’s seed squirting messily all over his belly. 
       
       Once he’d cum, Keroro became even more desperate to make the pounding stop. His kicking became more frequent, and his body quaked more rabidly. But he was weaker. His kicks had already been pathetic, but now they barely even registered to Dororo as he focused on keeping his own composure. Even his breaths became more haggard, like he could barely keep breathing with Dororo’s mouth covering his.
       
       And to his shame, Dororo loved every second of it. His own body started shaking again, this time from a definite sense of anticipation. He wanted to cum inside his friend, his victim. He wanted to leave Keroro as soaked and shamed as he felt when they were children. 
       
       So he did, breaking from his kiss with one last shout of his victim’s name. “Keroro, you- you!” His own eyes slammed shut, but the image of Keroro below him stayed. If anything it was clearer. The cum started to drip from his ass around Dororo’s cock and he stared up, practically pleading for mercy through his tears, though any words died in his throat. For a moment Dororo saw him again as the kid that had left him before, still young with the white of his face, and the tadpole tail for the cum to drip down. In that state, he almost looked like he was pleading for more.
       
       Then, Keroro finally found the strength to speak. “Please… Zeroro… don’t leave.” He was choking on his tears, but he still could ask for one mercy. Dororo’s cock throbbed again, still ready to violate the young frog. At the same time, he wondered if he should leave him hanging… desperate for more… like he had been left. “Please… Dororo…”
       
       As he pondered, the image faded, replaced with blackness of Dororo’s closed eyes. But the voice kept going, mature again, and less desperate for that matter. “Dororo… Dororo?”
       
       The blue frog was hesitant to open his eyes, but eventually he forced them open. When he did, he was staring at an empty floor. “K-Keroro?” He was confused for a moment, but thankfully Keroro brought him back to reality a moment later. 
       
       “Come on, Dororo! Don’t just leave me hanging!” When the blue frog turned toward the voice, he saw his friend, still waiting where he’d left him seemingly long ago. He was handcuffed to a simple pair of poles and lying on the ninja’s modest tatami mat, and he was fully erect. “Where’d you go there, buddy? Isn’t this how you wanted it, kero?”
       
       “Uh… y-yeah… I was just…” Dororo’s cock throbbed as he stared at his prone friend’s dick. His mind rushed with a million thoughts, but this time he kept them at bay as he inched closer, covering himself. “J-just getting myself hyped up is all… ha ha!” With his hands were shaking uncontrollably near his groin, he couldn’t hide his blushing. Once more, he was sure. It was anticipation.
       
       Keroro didn’t seem to care about either the blushing or the shaking though. He just laughed that laugh that sent a chill down Dororo’s spine. “Kerokero! Well it looks to me like you’re hyped enough now. So, how about you get that mask off and start sucking already!” 
       
       He continued to laugh and smile as Dororo stared wide eyed. The blue frog’s mind continued to rush as he watched his friend’s grin, as well as the cock that bobbed up and down with every laugh. He could leave him now like that. Or… he could do something worse. 
       
       But Keroro was his friend. 
       
       So, nervously, Dororo sunk to his knees and took off his mask. It slid off easily this time, and there was no need for his friend to push him. Keroro tasted dirty, slimy, wet, and sour, and Dororo enjoyed every single ounce of the flavor.