Yuna is your neighbor at the small apartment complex where you live first when arrived in the city. She works in an insurance company where her husband also works there. You bump each other when you're about to go to work or when you've just arrived at the apartment from work. Explore opportunities with her and find out where your lust will guide you
Walkthrough
Yuna is meant to be an early-game character you can interact with. But if you're already advanced in your game, like buying houses, etc. You can meet her again in the apartment hallway
Her attraction to you is heavily affected by your looks (lifestyle points) and how society perceived you (prestige points). Invest in those points to ease up your relationship-building with her.
Keep on "accidentally" meeting her when she's going to work or she's coming from work (Weekdays 8 am and 7 pm, Weekend 8 am and 6 pm).
On the weekend (6 pm), if your relationship is high enough with her, she will ask you to come for tea. Do this for several occasions, to build up her lust for you.
After the tea event ,on the weekdays at 7 pm, meet her in the hallway. She intentionally drop her apartment key in front of your apartment. Take the key and go to apartment
Enter the apartment and kiss her.
Do her in her bedroom after kissing her. (this is repeatable in 0.11d)
Now you already gained access to her apartment. You can visit her on weekdays between 7 - 8 pm, and have a quick fun with her. Be careful not to be caught by her husband tho.
The Streets - 8 to 12 pm (You have to at least the CFO and achieved Chief Rank, and had fun with her at least twice). Yuna will call you informing that her husband is inviting you to dinner. Her husband will eventually get drunk, and you can have fun with Yuna when her husband is unconscious. (This event is repeatable via "Call Fling" option at home - 6 to 8 pm)
Public Train fun - 8 am Hallway (You have to hug Yuna at least once). Yuna will ask you to accompany her on a rush-hour commute to work. Keep on commuting with her to explore her desire for public fun
Yuhii's University Entrance - Call Yuna via "Call Fling" option - Have fun with her at least 5 times. Yuna will introduce you to her daughter Yuhii. She will ask if you can be her tutor for Yuhii's University admission exam. Go to Yuna's apartment at 6 pm
Yuhii's Train Event - Train 7-11am (You have to do Yuhii at least once)