Cengjing You Yongshi

A dragon with a maxed-out combat score, yet single-mindedly prepared for death and yearning for a comfortable retirement, the demonic realm's foremost king-killer, Ell, encounters the cunning human magician Lefey and, through a series of twists and turns, becomes the super-dad raising Lefey's son, Dino. Will Dino remain an ordinary, happy child, or will he bravely raise the Warrior's Holy Sword and face his fate? (Source: Bangumi, translated)