Obanai is deeply in love with Mitsuri, as he's stated in the manga. He feels as if he can't tell her, however, because of his "filthy blood", caused by trauma in his past. He first saw her when she stood under a sakura tree, which is where he fell in love with her. To show his affection, he gets her gifts, such as food or the socks that she wears in her uniform. Even though she is the Love Hashira, she is unaware of his infatuation, causing his love to be unrequited. They frequently exchange letters.
He is very observant of Mitsuri, as he is immediately able to tell when Mitsuri is feeling down, as well as what food and how much food she normally eats.
When fighting against Muzan with the other Hashira and Demon Slayers, Mitsuri is injured. Obanai instantly rushes to her side, taking her away from the battle to get help. As he leaves her with the other Demon Slayers to go back to the battle, she is seen screaming his name, begging him to come back alive.
After the battle with Muzan, Obanai is seen cradling Mitsuri's body but, although both are still alive, they already felt that they were going to die soon. Obanai and Mitsuri reminisce about the first time they met at Ubayashiki's mansion and how Mitsuri saved him by making him feel like a normal young man and how he won't let anyone say anything bad about her. In the end, Mitsuri confesses that she loves him and that the meals she ate with him were the best. She also states that he has always been looking at her so gently and asks him if he'd take her as his wife if they are reborn as humans again, to which Obanai replies that if she's fine being with someone like him then he'll definitely make her happy and that, next time, he will protect her for sure. This vow eventually happens as their reincarnation is married to each other.
During their first meeting, Mitsuri thinks to herself how Tanjiro continues to protect his sister, despite her becoming a demon, calling it beautiful sibling love.
Mitsuri likes Nezuko, as she is seen playing with her during the Swordsmith Village arc.
- ↑ 1.0 1.1 Kimetsu no Yaiba Manga: Chapter 188.
- ↑ 2.0 2.1 Kimetsu no Yaiba: One-Winged Butterfly, Chapter 3.
- ↑ Kimetsu no Yaiba Databook.