Tsukikage Baby - Vol. 1 Ch. 4

[MangaDex]

 

[Weasalopes]

Speculation:

She's your cousin.

While your uncle never married, he still has a daughter.
And she, her mother, and your uncle all know about it; he's been visiting all her life.
But no one else knows.
How this was concealed from everyone in this town, I've no idea.

This... would explain everything. Absolutely everything.

It'll be interesting to see if I'm right about this.

 

[Beregorn]

@Weasalopes I REALLY hope that's actually parental love... Also I seem to recall that he is not actually his uncle, but a guy that sort of adopted him

 

[Weasalopes]

Let's just say future developments proved my speculation to be in error.

I did enjoy where the author went with it.