Responses
Following... Wait does the title has the word "diary" or something?
I think this is the one you are talking about....
http://www.mangago.me/read-manga/zui_wu_dao/
Thank you so much shadowninja!! That was it!! Super thanks. (๑•ㅂ•)و✧
Welcome... ╮(￣▽￣)╭
Looking for another manga. Forgot to save it to my list! It is a karate manga where the boy is weak in his world and not very talented but then meets his "master", which is a floating cat. Oh and he gets his arm turned black and people are trying to get it. Then they go to another dimension to become the best fighter and find all the treasure and stuff. And he eats the monsters he fights to gain power.