The protagonist is a middle-aged, single salaryman.
He’s been having secret hotel dates with his niece, Mifuyu.
Once, after parting ways with Mifuyu, he’s ambushed by another niece, Mana.
"Give Mifuyu back!"
Mana had heard from her mother (the protagonist’s sister) that her uncle was a "hopeless loser," so she couldn’t understand why Mifuyu liked him.
If Mana were left unchecked, his and Mifuyu's relationship would be known to the entire family. Mifuyu tried to reason with her, but Mana wouldn’t listen.
At her wit’s end, Mifuyu came up with a last-ditch plan.
"Alright, then… how about the three of us go to a hotel together?"
Will this mark the end of the protagonist’s love life with Mifuyu?
What will become of the three of them?

[Translated from the official website]