The Revenge of the Soul Eater

Hangyaku no Soul Eater
反逆のソウルイーター

Source

Revenge of the Soul Eater: Cast Out as a Weakling by My Sword Saint Father
Hangyaku no Soul Eater· 反逆のソウルイーター
novel

Sora Mitsurugi's life isn't going as planned. Disowned for incompetence by his renowned Sword Saint father, dumped by his fiancée, and banished from his island home, he sets off to prove himself as an adventurer on the mainland. But when his new so-called-comrades deceive him and use him as bait for a dangerous monster, he finds himself on the precipice of death. Just before his demise, a raging power courses through his body and he is reborn as the legendary dragon, the Soul Eater! Now, with his newfound strength, Sora is out for revenge! (Source: J-Novel Club)

Alternative

The Revenge of the Soul Eater
Hangyaku no Soul Eater: Tamashii no Hoshokusha to Shoujotachi· 反逆のソウルイーター -魂の捕食者と少女たち-
manga

"We have no use for weaklings here!" "I will become a strong swordsman," but contrary to his childhood wish, Sora was banished from the Goken family, masters of the Genso Itto style of swordsmanship. Branded as useless and having lost everything, he becomes a “soul-eating dragon” and vows revenge! (Source: Comic Earth Star, translated)