Headphones Samurai

Following his younger sibling’s last request, he searches for Lee Haeseung—the woman believed to be the child’s biological mother. A DNA test reveals an unsettling result: no parent–child match, yet the same maternal lineage. Drawn to the pale, fragile woman hiding secrets beneath the afternoon light, he must uncover the truth behind a bold transgression. Original Webtoon

After a god screws up and accidentally takes high schooler Shou's life, he offers him reincarnation with a gift to make up for it. Shou asks to retain all his old memories for the new life. Shou is reborn as Will, a noble's son in a world where magic use is common and involves knowledge of kanji characters. With all his memories, he's a brilliant toddler, and when he experiments with magic, he finds that he has an amazing talent for it! What's more, though he was smart but unloved in his old life, in his new life he has a mother and a father who both love him deeply. His future as Will is looking very bright!