Ryu Ga Gotoku fan has the extended video:
Here
Which shows clouds moving in the sky at night and during the day representing the passing of time, glass and liquid physics for drinking and bits of the heat effects when Kiryu triggers his heat mode.
I've always had the idea of the Yakuza series to have real time day and night cycles in which the behavior of npcs changes based on what time it is.
Examples:
Early morning: Npcs going to work, kids going to school, sanitation workers picking up trash, restaurants start making their breakfast/day menus and night shift workers going home.
Day: Stores more populated as npcs are shopping and going to restaurants for lunch, in which it seems a npc's taste can change, like some days there would be more people in smile burger and the next day more people at Kanrai, also restaurants could have random specials which you can read about in magazines in the gourmet guide.
Evening: Npcs come back from work and school and are hanging out in places like Theater Square and going to Sega arcades or going to bowling, speaking of Theater Square, I would make the movie theater an actual place you can go into and watch previews of upcoming Sega games or even past trailers of the RGG series or even to reminisce and watch cutscenes, restaurants start their night menus and kids can play in the parks.
Night: Night workers come out as Kamurocho starts lighting up, kids have gone home and the ones still around are the delinquents that includes gyaru and gang types, the night shift takes over and npcs are frequenting bars or drinking in the parks, usually more Yakuza and thugs are patrolling the streets looking for fights, during the course of the day trash has built up and you have more homeless foraging through it, hostesses can be seen out on dates and you see more couples in the hotel district.
Late night: Drunks staggering home, stronger specialized enemies at night and generally less people around expect those looking for fights or to hurt/kill people.
Add in dynamic weather that changes and not scripted unless for the main missions or substories plus npc clothes can change so besides umbrellas they could also wear raincoats or even winter or summer clothes and that could be pretty good but that would have to be some engine to do so.