Our main character, Ryuu Otoha, died in modern day Japan. He was reincarnated in another world as a monster that was among the weakest. Closer to a normal beast, a snake.
This small frail snake was picked up by its owner, a girl with a large chest, and it is for her sake that it aims to become a proper dragon.
Raw: https://kakuyomu.jp/works/16818093090619184366
Part one – Cunning dragon
Chapter 9 – The second evolution
Chapter 11 – The elderly villagers
Chapter 15 – Battle between C ranks
Chapter 18 – Your dragon alone
Part two – Weak overcoming the strong