what sort of hobbies / past times does masamune have?
Having the shit beat out of him
Obsessively practicing with his swords
I think these are all rather self-explanatory .. or not. Masamune is an intensely physical individual -- however there is a pattern to be seen: he is always the one who makes contact with others, and unless the contact is violent NOBODY touches him. Ever. He grew up in violence. He developed alongside bloodshed and it’s a part of him. There is a stark difference between Masamune on the battlefield and him having a spar with another -- he enjoys it. The sweat, the exertion, the thrill, the comfort in camaraderie through one of the few things he knows deep inside his marrow. If he spars with you, he is not aiming to kill you. It’s for the fun of it all, something there is no chance of when at war.
Cooking is something he enjoys; though not a savant at the stove, he is certainly not bad, and finds it relaxing providing for himself where others typically do it for him. For guests, he finds particular pride in cooking for them himself, actually! It’s relaxing, cathartic, and requires that flair of artistry he craves in everything he does. He’s an artist of the sword, and aspires to be a chef; though he may never reach a professional level of skill (as he hasn’t the time to indulge in such activities -- he is a Warlord, after all), it’s something that requires thought, and quiet.
Sex is again, self-explanatory. His habits themselves are particularly fascinating, but Masamune is BI-SEXUAL AS FUCK. He will indulge in knife-play, blood-play, all of that, assuming that he doesn’t particularly care for you. Once he does care though, all that’s out the window unless it’s directed on him. Weird shit OK.