Tanjiro

Though Tanjiro and Kanao liked each other very early in the series, they only fell in love after the war against Muzan and his Twelve Upper Moon. It's unclear how things progressed between them, since the manga ended with them going their separate ways ...

Though he was initially trained to use the Water Style, Tanjiro inherited the Kamado Sun Breathing Style from his father. This makes Tanjiro the last known Slayer to use the Sun Style and the only known Slayer who switches between two styles.