A manga where a guy, his childhood best friend and (I think) three other guys get transferred to another world. And the MC has 10 skill slots. The three other guys bullied him back on Earth.
When he got transferred over, him and his childhood friend (it's a girl) both got 10 skill slots that they can fill up by people or monsters dying and them dropping their skill cards.
His girl best friend betrayed him to survive by siding with one of the bullies. The MC got pushed into a dungeon where time goes like 500 times slower.