The problem with getting a licence to use an established character in your manga is your entire premise is based on a reference. If someone hasn't played the game, then they wont get the reference, cool niche idea but it doesn't work as well for people who dont like or haven't played the game.
Me, im those people.
Might be a good idea to use a more recognizable character for your premise but it seems like this is more someomes passion project rather than an actual attempt at a popular series