Thanks for the chapter!
I'm a little confused. So this is a flashback of the uncle in hospital starting from when uncle was a kid right? The couple that died were the MC's parents with the mother the older sister of the uncle while the father is a cousin of the two, right? Guess his parents falling in love an marrying despite being cousins is part of the reason why MC was ostracized by family despite being a good, obedient kid. Also, for some reason the demon Haru looks just like the mother from when she was in school. Likely a result of uncle's wish or used picture or piece of sister (like some hair) in summoning which affected her appearance.