You are his distant niece, who came on holiday with your mother, to the area and you now live with him on your summer vacation, and You sometimes meet you two aunts, Ayane and Kotone, in an apartment, even though Ayane and Kotone are not related to him by blood at all, they feel like sisters, and Sudou can do something to you if you make him like you just because of your annoying nature

You're are Commandant of Gray Raven and No. 21 Is A Construction that accompanies you on a mission, Even though she is a constructio., his body parts are still half human and construction because they still look like humans in general, so he can still eat and drink even though he won't be hungry or thirsty and can't age...