Rion Yamashiro (山城 理音 Yamashiro Rion) is a class A player. She joined the karuta club of Fujisaki High School. She is also the granddaughter of certified reader and Level 7 karuta player, Kyoko Yamashiro.
Rion has short red hair cut in pageboy style, and pale brown eyes.
She appears to be a timid person who rarely shows emotions. She is actually a big eater, and the main reason she plays karuta is the rice she is bribed with.
Rion and Chihaya faced against each other in the team finals for the National High School Karuta Championship. Rion did well against her at first, until she injured Chihaya by accident. After that, Rion's hesitation and Chiaya's burning desire to win gave Chihaya the edge to beat her.
Chihaya chooses chocolate as her go-to snack in between matches. Rion would rather eat onigiri. Their food choices have become a point of contention when Rion left her bento at home and Chihaya offered her chocolate to eat.
Makoto thinks that Rion is a strange girl because it's pretty rare for Rion to show her emotions. He harbors feelings for her, but tries not to let it show. He thinks she is copying his hairstyle.
Midori is Fujisaki High School's karuta club advisor and coach. She allows Rion to play in the group final against Mizusawa rather than an A Class player.
Rion played Taichi in the final match of the individual tournament of Class B. Taichi ended up winning against her.
Rion is finely attuned to her grandmother's reading style. This leads her to prefer her grandmother's reading over other readers. She is fast, with agile and light hand movements. Unfortunately, she lacks stamina and motivation.
- Chihaya gives her the nickname "Yama-chan" during their match together (in her mind), because she couldn't remember her full name.
- In Chapter 94, Rion reveals why she's playing Karuta. She is also called 'master of rice' there.
- By Chapter 96, she makes it to Class A by being placed 2nd in two class B tournaments.
- Her big appetite is balanced by her high metabolic rate.