What would've been a complete arch for Matthias for you?
I found his story rather unsatisfactory, like it had a start but didn't actually have an end. I found it rather difficult to believe Ninomiya wouldn't have tried to kill literally anyone else, and rather odd Matthias death wasn't really on anyone's mind.
Like with Ogura (do not get me wrong her story wasn't perfect none of it was its tetro) she had a whole god falling from grace, failing to protect a friend previously so feeling an even greater need to protect others than she already did ect ect... But I just find myself coming up rather short with Matthias. He's a character who has a great love for the world and a deep capacity for empathy and forgiveness, who as we can I am sure agree his side story with Ikeda completely died in the water (and yes if I could've changed anything I'd of had Ikeda apologies to Matthias 100%, but thats a side story not the main thing ykyk)
Idk I just felt rather bored with his final direction.