Is it possible to make games on hit anime's like bokuno hero academia, naruto.. Without facing any copyright issues?
If no, what all specifications should I look forward to cater?

Yes if you keep it for yourself and let people play at home.
No otherwise, but contact the creators. I once got assets for a game from another game studio because I wanted to port their game to pc.

Not a lawyer

Something simple like a flappy bird but with ani me characters

@Codex404 but I want to publish it too

@electric-ghost maybe in future, if the game's a hit, I would like to monetize it. But not for now. Anyways I guess, contacting the creator is the first step needed

@ardnahcimor then contact the creators.

Pretend it's about different (similar) characters or ask for permission. If you use their work you need their "okay." obviously.

For case one, there were successful stories (Arial & Helvetica, Segoe UI & Frutiger) and cases where the copycat got fucked (Mobile Legends got sued by Riot games)

@D--M I dont know WHAT. THE FUCK you have read but most comments say there are copyright issues....

@Codex404
You all gave retarded answers like;

"If x then its okay"
Or.
"X does it, so i guess you could"

When the real answer to give OP is a straight "yes there are issues, dont do it" because obviously he has no idea wtf he is doing.

@D--M if you are making it for just your household its allowed.

Otherwise you need permission. So yeah the IF x is needed.