It is the obligation of those born strong to defend the weak. Your mission requires you to fulfill your mission properly. Don't ever forget that.
Ruka has defined facial features, such as her sharp nose and long eyebrows. She has large dark red eyes with circular white pupils, similar in appearance to the Kamado family, and a small mouth, with semi-long black hair tied loosely at the end in a ponytail.
She is only seen wearing a traditional kimono in a series of flashbacks.
As opposed to her husband Shinjuro's loud personality, Ruka is depicted as being wise, gentle and graceful. In the manga, she is seen having strong morals, teaching Kyojuro the importance of his life and the need to use his strength in order to protect the weak and helpless people in the world as his primal duty.
Later, her husband speculated that their two sons have wonderful personalities mainly because of her biological influence.
Ruka is the mother of both Senjuro and Kyojuro, and is the wife of Shinjuro. Some time after giving birth to Senjuro, she developed an untreatable disease and was left bedridden up until her death.
During the confrontation between her son, Kyojuro and Upper Rank 3 Akaza, the Flame Hashira received a mortal wound and he recalled a last conversation he had with his mother shortly before she passed away, in which he never ceased to emphasize the values that he loved. These words motivated Kyojuro to draw strength from the depths of his being (despite the seriousness of his wound) to try to behead Akaza before he fled. Shortly after when Kyojuro was practically on the brink of death, he sees his mother for the last time who congratulates him on his task before Kyojuro passed away.
As an ordinary human, she doesn't possess any superhuman powers or abilities.
- Ruka's first name contains the On'yomi reading for the kanji for both "lapis lazuli" (
瑠ru?) and "fire" ( 火ka?).
- According to the pamphlet given in select Japanese theaters for the Mugen Train movie: For Ruka and all wives in the Rengoku household; a tradition of theirs is for women during pregnancy to stare into flames for hours without end, periodically as a charm to make their child grow strong, it is also a mythical explanation for why Ruka's eyes are crimson red. It is called "Kankagari" (
- (To Kyojuro Rengoku) "People who were born and blessed with greater abilities than others, have to use their power for the world, for the people. Hurting others with your power which was gifted from the heavens, and soiling your clothes is unforgivable. I will not be alive for much longer. It was a blessing to become the mother of such a strong, gentle child."
- (To Kyojuro before his death) "You did a wonderful job."
- (To Kyojuro Rengoku) "The Rengoku Family has hunted demons for generations. And becoming Hashira is our pride. Like your father, you will become a great Hashira. Bear the flame in your heart. Burn evil demons and shine gently on human beings. Hold your heart a flame like the sun. Become the Flame Hashira."