DREAMERS12

Its just my theory may be she intentionally become friends of them and told them to wait and go. Actually in current situation I only think about the owner and the teacher.

I think the shop gets busy after evening she may be stalk them during daytime & killed all pf them at night after closing shop. Or the Homeroom teacher that wears a military-like uniform could be killer. Lets see what will happen next may be in between 11-12 episode we will get more hints

But every victim last located at tea house. So I think she is some how connected and always the less predictable character become killer on this kind of genre.

Me too. As in the 1st episode the writer hinted killer can be a woman too

At episode 6 the uncle of FL become suspected person

yes

I googled for the same reason it says Blood donation from close relatives could lead to Post-Transfusion Graft Versus Host Disease (PT-GVHD)