How would you rate the bsd mens‘s stamina?
At the top? Chuuya, obviously, and Lovecraft.
Chuuya does NOT know the meaning of getting tired, or cramps. He can bend both of you into pretzels and go for hours if he feels like it, and it doesn't matter how heavy you are because he'll move you like you're nothing. He usually stops bc his dick starts hurting from overstimulation and he's not the biggest fan of it.
Lovecraft straight up can't get tired. Whether he's in human form or something more monstrous, his body works on a completely different power scale. You're like a speck of dust to him, and your lifespan that of a fly's. He can't get tired in any way that you can comprehend and even if he did, he can simply switch to another set of limbs and keep going. He gets his satisfaction from making you fall apart.
Pretty high? Nikolai, Atsushi, any of the hunting dogs
Nikolai would be able to last longer, if he didn't insist on going ballistic every single time. I don't think he knows what restraint means, he's always up for weird and strenuous positions that end up tiring him out. And don't get me wrong, he's strong, but I don't see him focused on cardio.
Atsushi my darling boy, another one who still has an above average stamina. You're still going to tap out before him every time, but I think longer sex sessions take quite a bit out of him. It doesn't help that he often transforms halfway through, pinning your arms down so he can mount you. By the time his knot has gone down he's already begun to get sleepy and cuddly, rubbing his cheek against your back and purring, so all the fight has gone out. But don't worry, in the event that you can still walk you can probably coax another round out of him, as long as you do most of the work.
The hunting dogs are variable, depending on what time of the month they're at. Remember all those surgeries they have to do to maintain their bodies? Yeah, if you catch them on the tail end of that they eventually get tired. They still last inhumanly long though, but might get creaky and achey joints afterwards. While on the topic of them being augmented I'd like to propose them having small dicks, since it's a side effect of steroids (and it will also happen when you take estrogen!)
Average? Kunikida, Fukuzawa, Mori
Not much to say here, they're not cardio specialists but they can still last. Who ends up worn out first comes down to how fit you are. Less strenuous portions like riding or spooning will help.
Abysmal? Dazai, Akutagawa, Fyodor
Sorry guys, but Dazai is not the CEO of sex no matter how much you wish he was. This man doesn't eat right, drinks exclusively alcohol, and hasn't exercised a day in his life. He's going to be panting like an asthmatic pug after two minutes, and god forbid you make him do all the work. Nope, make him do core exercises and take him biking.
Akutagawa has a lung condition and is also built like a stickbug. I believe he eats moderately well thanks to Gin, but he's no stallion. Take care of your frail Victorian man lest he be taken by consumption. However, using Rashomon helps immensely since it's not taxing on his body, plus wearing the coat makes him more comfortable.
As for Fyodor? Don't even bother. 0/10. Would not recommend. You can do better.