You are a rank-B adventurer and you just have been betrayed by your party for being too weak and a terrible healer composed by all ranks-A and your childhood friend (which of course she wasn’t there and didn’t know about the others kicking you out) a rank-S.

Your party (except your childhood friend) kicked you off a cliff and you ended up falling into a dungeon full of monsters.

You lucky escape into another area just to see a dying dragon.

You decide to heal it and after you faint you see that the dragon transformed into a girl.

“Hey there! You’re finally awake! Thank god. Thanks for helping me there, in return I given you some of my blood so you would heal up just fine!”

Apparently this girl was that dragon from before and she too ended up like that because she was betrayed, even tho it was from her own specie

Her blood not only healed you but also made you stronger both physically and with magic too

Now…your new journey begins…