Chapter 177

Younger Brother is the one hundred and seventy seventh chapter of Koyoharu Gotōge's Kimetsu no Yaiba.

Summary
Kokushibo remembers his past with his brother Yoriichi Tsugikuni and says that those who do not envy orhers are merely lucky as they have not encountered someone who was so strong and vivid that they scorched everything else as if they were the sun.

He thinks back to when they were born and says that in their time twins were considered unlucky as they caused succession disputes. Yoriichi had been born with a mark on his forehead which was considered hideous and his father had ordered for him to be killed, however upon hearing this news their mother had been enraged at him so it was decided that Yoriichi would be sent off to a temple when he became ten years old instead.

The brothers were kept separated and Kokushibo (then Michikatsu) would often see Yoriichi clinging to their mother's left side and he had found his younger brother to be pitiful and childish. Michikatsu would sneak to Yoriichi's room when their father wasn't looking and even made him a flute. People had believed Yoriichi was deaf as he had never spoken a word until the age of seven.

One day while practicing sword swings in their garden, Michikatsu was chilled to the bone to notice Yoriichi staring at him silently from next to a tree. Suddenly, Yoriichi spoke and asked him if his dream was to become the strongest samurai in the country. Michikatsu was so shocked he dropped his wooden sword and Yoriichi burst into a smile and said he would become the second strongest samurai. However, Michikatsu was merely disgusted at his brother's lack of awareness that he would only go to a temple instead of becoming a samurai, saying that a kid who ran to his mother everytime he saw her could never become a samurai.

Yoriichi began to hang around Michikatsu's sword practices and asked to be taught their way as well so Michikatsu's trainer gave him a small shinai. With basic instructions on how to hold the sword and form a stance, the trainer asked Yoriichi to charge him. To Michikatsu's shock, Yoriichi was able to shatter the trainer's wooden sword, flip him over and knock him unconscious in only four swift strikes. The trainer even grew swellings the size of fist in the spots Yoriichi had struck him.

After this incident Yoriichi lost his desire to become a samurai as he disliked the feeling of hitting someone and felt horrible for it. Michikatsu was greatly intrigued at his brother's strength and tried to learn his secret. After much coaxing, Yoriichi said that their opponent's lungs expand, so they just had to closely watch their bone movement, muscle contraction and blood flow. Michikatsu had difficulty following this but was able to surmise that his brother could see through living things' bodies. He felt jealous that his brother had such immaculate talent to fight with but absolutely no desire to fight as Yoriichi told him that he would rather just fly a kite with his brother.

Later on Michikatsu realized that his positions with Yoriichi would become reversed and he would be the one that would have to live in the temple instead. However that night, Yoriichi came to him and told him that their mother had passed away and that he would be running away from their home for good, saying that he would always cherish the flute his brother had made for him before running off.

The next day Michikatsu read their mother's diary and saw written in it that Yoriichi had realized he would become the heir which is why he decided to leave their house earlier than planned. He also learned that Yoriichi was aware of their mother's illness and that she had been suffering pains in her left side for several years. Michikatsu made the connection between her illness and Yoriichi's constant clinging to their mother's left side whenever he saw her and realized that his brother had in fact been supporting their mother the whole time, crushing the page as he lost control of his jealousy.

Characters in Order of Appearance

 * Kokushibo (flashback)
 * Yoriichi Tsugikuni (flashback)