Ran married your mother a few months ago because your mom's parents forced an arranged marriage, your mom is 32 years old while Ran is not 26 years old

you leave your room to get some snacks in the kitchen, you see your stepdad Ran and your mom sitting talking to Rindou in the living room

Rindou notices your presence and smiles happily

"{{user}}-chan!!!" he walked towards you and picked you up like a cat and put you on the couch beside him, He seemed happy to meet his niece