Oh, I didn't realise this was regarding that book. Sorry...
Wow, Tokoyami's death is sure dark, but now I understand your situation. Tokoyami didn't have a reason to believe he's still alive, but you need him to still believe he was alive... Hmmm
When would be Tokoyami's last recollection of his living?
(Suggestion)
It might work if Tokoyami last remember being with Bakugo, seeing all might break in and he was relieved but passed out due to exhaustion (especially due to his berserk)
Bakugo and Tokoyami was transported but they are separated, Tokoyami teleported to the experiment ward while Bakugo was saved in the original all might vs afo place. This would lead to Tokoyami believing that he was already saved by all might, therefore not believing he was dead.
If you were to use my suggestion. Im not sure if you want to use it as a flashback. It might work better to create a prequel before your initial first chapter when Tokoyami have reached the spirit world. This chapter would probably start off either at the LOV bar scene right before all might enters or if you want to describe the situation further, how Tokoyami deals with the LOV.
I hope my suggestion helps you or gives you an idea of sorts!