Forget about hidden items and mojis. Just speed run the game.
Use the Heavy Hammer weapon to kill all the bosses!
For the spider round 2(when you have to break it's legs and you need to crack it's shell), if it's annoying you, just use your dual blades and perform RT+Y. Ken will jump in the air and does a spinning move. This will eventually kill him without cracking it's feets.
Don't forget to use your adrenaline for the spider, dies quicker.