Isshin doesn't really bother with analysing the hows and whys of his partying ways, but certainly takes part in every liquer run, bar crawl, and roof-raising dance party. Sometimes he even gets Ishida to come along, if only because he's hosting the party in their home.
Their home for the past year has been a simple two-room apartment like most in the city's area, but it is right next door to a thriving karaoke bar that never fails to draw too much of Isshin's attention for Ryuuken to like it.
He is also always the one who ends up cleaning up the cans of beer and cigarette stubs at the end of the night, in addition to phoning taxis and relatives and roommates to get all the ones too drunk to bus or subway home. And then he has to deal with Isshin, who is all clingy limbs and slobbery kisses that nearly always miss their target.
Nevertheless, years later, when Ryuuken is sitting in his much larger, sterile-white apartment alone, he sometimes wishes he had an Isshin to barge in and drag him out by the elbow away from his work to dance awkwardly in a room much too small for too many people. He wishes sometimes that he could enjoy the smell of cigarettes and alcohol and sweat once again before falling asleep, even as disgusting a mix as it was back then.
Most people wince when they think of their younger, partying days - Ryuuken wishes he had taken what was there when he had the chance.