Hello Anon! Sorry for the late reply.
Fukumori is definitely not a fan of extreme way of spending time, and they're both almost always busy with work, so they would spend their free time either at home or not far away from it.
Can't imagine them sleeping until noon, then ordering takeout, and then going back to bed. I think they'd physically hurt them if they spent their weekends lazily...
Mori would try to use the time to bond and better understand each other, like cooking together, watching a movie together, taking walks in a nearby park, getting a massage together... and Fukuzawa would just want to relax, Ougai wouldn't be a big part of his plans. I imagine they'd try to find new hobbies in their leisure time: I'm sure Fukuzawa would go fishing; BIG headcanon on him enjoying wood carving. I think Mori would be interested in writing, perhaps something he could spend a long time sitting and working on, developing fine motor skills, like puzzles, mosaics, or paint-by-numbers (i hate them), but not often really. He'd enjoy visiting museums, i guess. He'd also deepen his medical knowledge, because I think he'd miss it after working for the Port Mafia for so long.
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I imagine they'd spend their leisure time that way.
(─‿‿─).....
gif just for fun
