Well, that was an adventure. Lemme put on some calming music before we get into it.

Pent up anger. Tenko Shimura felt his family was against him. Felt his father was a monster for punishing him for wanting to be a hero. Felt the rest of his family stood by and let it happen. This was the result, an angry child lashing out with a newly emerged quirk. A quirk that kills.
We knew Tenko would kill his family but I had my doubts. Namely, how did every family member keep their hands if they were turned to dust? Well, the answer to that was pretty simple. Decay, when it first manifested, broke things down into chunks, rather than disintegrating them like what we see from the current Shigaraki. Guess someone’s been training their quirk over the years.
We also see Tenko using a long-range attack and decaying his house (the one his father had built), confirming he’s been capable of doing those attacks from the beginning. And, while attacking, Tenko’s hair is turning white and I assume his eyes are turning red, just like Eri. If All For One had nothing to do with Tenko’s quirk then that confirms someone with a mutant quirk gets those physical attributes only when their quirk first activates.










