Sayonara Ryuusei Konnichiwa Jinsei (Novel) summary:

The oldest and strongest Dragon grew tired of living choose to die when the Heroes come for his life. When the Dragon's soul is waiting to drift toward the Sea of Soul, that is when its noticed its has been reborn into a Human baby. The Dragon then decide to live it's life as a Human to the fullest, and regained his will to live. The Dragon was born into the child of a farmer lives his live in the frontier possessing enormous amount of power due to his soul being a Dragon's. He then encounter the Demon of the Lamia race, fairies, Black Rose, and later enter the Magic Academy. The man whose soul is of a Dragon lives his life in joy going to Magic Academy, spending time with an old friend, The Earth Goddess, meets beautiful girls, strong classmates, the Dragon King and the Queen of Vampires. Original Web Novel