Stepsister Shock!

Stepsister Shock! (2020): Visual Novel. Developed by Genius Studio Japan. Available on Android.

When your mom tells you she's going to remarry, you feel nothing but happiness. That is, until you find out who she's getting married to! The new man in her life has three daughters, one of whom you've known since you were a child... Your everyday life has gone from dinners alone in front of the TV to fighting over who gets to take the first bath. But this new life isn't all bad, especially considering how cute your new step sisters are...