It’s the duty of those born powerful to protect the weak. It is essential that you carry out your mission correctly. Never forget this.
Ruka Rengoku to Kyojuro Rengoku, Chapter 64

Ruka Rengoku (煉ごく瑠る火か・煉ごくる Rengoku Ruka?)[1] was the wife of Shinjuro Rengoku and the mother of Kyojuro Rengoku and Senjuro Rengoku.


Ruka has well-defined facial features, such as a pointed nose and long eyebrows. She has large dark red eyes with circular white pupils, similar to those of the Kamado family, and a small mouth. Her medium-length black hair is loosely tied in a ponytail.

We only see her wearing a traditional kimono in a series of flashbacks.


In contrast to her husband Shinjuro’s boisterous personality, Ruka is described as wise, gentle and graceful. In the manga, she is seen to have strong moral values, teaching Kyojuro the importance of his life and the need to use his strength to protect the weak and defenseless in the world, seeing this as his primary duty.

Later, her husband speculated that their two sons possessed wonderful personalities, mainly due to her biological influence.


Ruka is Senjuro and Kyojuro’s mother, as well as Shinjuro’s wife. Some time after giving birth to Senjuro, she contracted an incurable disease and remained bedridden until her death.


Arc of the Infinity Train

Abilities and powers

As an ordinary human, she possesses no additional supernatural powers or abilities.

Ruka Rengoku | Demon Slayer Kimetsu No Yaiba


  • Ruka’s first name contains the kanji for “lapis lazuli” (瑠る ru?) and “fire” (火か ka?).


  • (To Kyojuro Rengoku) “People who are born and blessed with greater abilities than others must use their power for the world, for people. Hurting others with your heaven-given power and soiling your clothes is unforgivable. I won’t be alive much longer. It has been a blessing to be the mother of such a strong and gentle child.”
  • (To Kyojuro Rengoku) “The Rengoku family has been killing demons for generations. The alias of Flame Hashira is the pride of our family. Now set your sights on becoming a wonderful Hashira like your father. You have a flame in your soul. Burn those evil demons to a crisp. Shine your light on people and keep that sun-like flame in your heart. Become the Hashira of flame.”
  • (To Kyojuro before his death) “You did a wonderful job.”

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