I will give a bit Walkthrough on what to do
Remember, this is a grinding game, so keep your head cool and be... patient...
1. Grind Trust (easier with playing games) until you can get bath together then take a bath together every day
2. I would suggest pursue the panties first since sister refuse to bath together anyway, you can keep loading if you get the same panties. And some exotic panties only show up on weekends laundry day.
3. Grind Interest with playing lewd games or perverted rpg
4. Test the interest and trust rates with small touching in the night (minimal energy 20 before sleep)
5. If Good > Bad, you can touch until she is awake. DO NOT penetrate yet (like I said, be patient...), just make her climax. After she climaxes, you can fap
6. Grind sexual encounter (every part of her body has pleasure experience level that will increase with every touch)
7. First penetration, but DO NOT shoot inside... especially if you are not ready financially... lol...
8. When everything is set (money, trust, mood, interest, dangerous day) > go ahead... claim her womb
9. Any extras can be find by playing the game; trying different things and grinding different parts...
If you have trouble with anal, just use the tongue to get the first climax. Then fingers can come to play.
Mood is important, so make her happy at all times.
In a way, this grinding game works with real life SO too... Big respect for Inusuku for creating a pretty accurate life grind.
I have a question, have anybody succeed on making the sister force the intercourse while she is a virgin?