After finishing 50 % of the game, he was transmigrated to the final hidden character.

***

While I was digging around the garbage dump trying to find a precious item that my colleague accidentally threw away, I found a game shining brightly as if it was calling to me.

So I took it and luckily, I also found my treasured item.
And so, I began my conquest and cleared 50% of the game in a single night. That was all I did. 

So how come when I woke up the next day, I became one of the hidden capture targets in the game?