ofc he is not the killer. The whole reason why aqua is searching for him is because he IS the reason why a stalker killed Ai...I think he's not the killer, at least if I was a killer I wouldn't come to my victim tomb bring flowers. I'm not this type of scum.
it comes from a feeling of going with what's being told not what's actually the fact. the double suicide happened when the older actor was young (since he was reised in a foster home)if he did indeed die a long time ago then how did he order the hit on ai later oni want to crush my skull into pieces and grind them until there is nothing but dust left, whats up with this plot twists man
Or it could be possible that Himekawa's mother was also cheating with someone else and had the boy. The husband found out, had an altercation and diedMy most basic guess for the loophole is that the father is the twin brother of the guy who killed himself. It would probably explain the same paternal DNA assuming they were identical. Hell, he might've killed his brother to fake his own death after killing his wife.
Could just be that the father is a second guy we don't know of and his half-brothers father got NTR'd, seems simpler"The simple loophole" that I believe Akane is referring to is a twin brother.