Kanao and Tanjiro would eventually marry and start a family, having two great-great-grandchildren by the names of Kanata Kamado and Sumihiko Kamado between them.
The peak of their relationship came when Kanao risked her life to bring Tanjiro back to humanity from his demon state (Chapter 202, April 2020). The series ended with Tanjiro and Kanao getting married and starting a family (Chapter 205, May 2020).
Tanjiro and Kanao's relationship blossomed slowly but eventually led to marriage and the birth of their descendants. Kanao's traumatic past and emotional stunting were slowly overcome...
Demon Slayer: Did Tanjiro and Kanao End Up Together in the Manga?
Tanjiro and Kanao's Relationship Fully Explained! (Demon Slayer / Kimetsu no Yaiba)
Tanjiro Kamado ends up marrying Kanao, a fellow Demon Slayer and the adopted sister of Shinobu and Kanae Kocho. After Muzan’s defeat, Tanjiro and Kanao eventually marry and start a family, having two great-great-grandchildren by the names of Kanata Kamado and Sumihiko Kamado between them.
While Tanjiro and Kanao enjoyed a close friendship early on in the manga, they did not fall in love until after the battle with Muzan, along with Muzan’s Twelve Upper Moon.
Kanao’s true importance in Demon Slayer became crystal clear in the manga’s Infinity Castle and Sunrise Countdown arcs, where she developed from a mere side character to saving the series protagonist, Tanjiro Kamado’s life.
Later on in the series, when they meet again on Natagumo Mountain, Kanao gets into a physical altercation with Tanjiro as he tries to protect his sister from getting killed and as result gets knocked out cold by Kanao.