Cumming on command was far easier said than done, and in Ken's case, even with the onslaught of pleasure coming from both sides, it was especially difficult. It was almost like he was trying to make his upcoming explosion worth the trouble it took to get there, on the subconscious level, of course. If directly asked, he wouldn't have minded a ruined orgasm that wasn't as intense or splash-worthy as the realest of deals. A submissive like him would have taken just about any degree of pleasure, overkill or nil, so long as he felt relief afterward and the domme who brought him there was satisfied.
Unfortunately for him, Mariko was not satisfied in the slightest. Even after everything she dished out to him thus far - the foot worship, the strap-on licking, the strap-on fucking, the whipping, getting fucked by the continually non-verbal Kiku, and ultimately this two-sided offensive - he still hadn't let out anything more than the occasional spillage of precum. It was no surprise she got upset with him. Performatively, but with the undercurrent of honest expression mixed in. Befitting of a domme, but especially so for one whose sub held as special a connection as Ken did for her.
That could be what inspired him to, through his grunts at the grab to his chin, he decided to stop holding back. He nodded weakly, and let out a few words, stuttered and strained by her firm grip. "Y-Yes... ojou-sama...!"
With a few more heavy breaths, he finally closed his eyes and grunted harshly, clenching his anal walls around Kiku's cock while thrusting his hips into Mariko's hand. The moment he did, the moment his inhibitions fell away. Almost squealing as he stifled his cries, he climaxed just as she ordered. It wasn't the strongest orgasm, but it wasn't nearly as weak as he thought it would be. Waves of pleasure washed over his mind and body alike, sending him into a state of ecstasy. Of course, this meant he had no idea where his seed landed. The remaining cognizant part of him expected it to land on her boots. Hell, he hoped it landed there! Seeing her sadistic side enter fuller form, demanding he cum while threatening to lock him in chastity, turned him on so much that he wanted more of it, if only for tonight.
Hell, maybe that's what finally convinced him to climax, and as strong as he did at that...