Ritsu is the source of fun and encouragement in her band, often making jokes, puns or pranks and being sarcastic most of the time. She has an ambiguous yet upbeat personality, but has often troubles remembering important club activities and announcements. Because of that, she constantly gets whacked by her childhood friend Mio Akiyama. Despite her forgetfulness, she usually brainstorms for ideas to earn more money or for the club's success in general (like blackmailingSawako Yamanaka to become the club's supervisor). Her attitude of collecting as much money as possible lets her sometimes appear greedy, something she greatly dislikes. Ritsu is always on the go and will stop at nothing for the success of the Light Music Club, even when everyone else gives up.
Ritsu is very barefaced, sometimes audacious or even impudent, yet she never has any ill minds and usually apologizes the moment after she went too far. On the other hand, she can't stop annoying everybody around her whenever the chance appears. Because of that, she has developed a certain endurance against Mio's hits.
From time to time, Ritsu has been a very lazy character as well. When it comes to practicing, she only thinks of having fun with her bandmates (such as having tea breaks that almost drove Azusa Nakano away). During training camps, Ritsu usually votes to play first the moment they arrive and is often supported by Yui Hirasawa. She is usually too lazy to study and often needs Mio's help (because of that, she actually scores good marks). On very few occasions, when the pressure is too high, she tends to give up and needs the help of her friends to continue. When she becomes determined however, she can get her work done in no time. Such determination can be seen on her goal towards Budōkan or attending her university of choice so she can study together with her friends. She also loves playing her drums despite being hardly willed to practice.
Ritsu has a liking for the band The Who and admires their drummer Keith Moon, although she dislikes his various past rampages. When it comes to music, Ritsu prefers rock. She also likes metal or punk; as long as it has a good beat, it's alright.
Ritsu is very athletic and has by far the best physical condition of all members of the Light Music Club. Physical Education is the only subject she is naturally good at.
Ritsu has a strong sense of confidence from an unknown source, although her confidence has often lead to the club's despair, such as when losing their way in the middle of Kyōto. A trademark of her is the habit of putting both arms at the back of her head. She is also very curious and therefore knowledgeable of many places to have fun at, a fact her friend Tsumugi Kotobuki admires. Tsumugi also described her as the type of person who walks the extra mile for her friends and who would be really popular among girls if she would be a boy (leading Ritsu to hit her out of embarrassment).
Ritsu has a tough front and would not cry easily. Her weak spot is seeing her friends cry and she would do anything to cheer them up, like denying the fact that she is crying too, despite it being obvious.
Ritsu is a surprisingly good cook and is also very creative, using a hexagonal pen in exams to use it to determine the answer she should choose, regarding the number she diced. In stressful situations however, she quickly looses her head and tries desperate attempts to save the situation.
Although she usually acts boyish and childish, she sometimes shows a girly and shy side, for example when she thought about Mio's lyrics to be a love letter for her or when she had to play the role of Juliet in her class' school act. She can also be very thoughtful, seen when she recalled her past.
When Ritsu gets in a bad mood, the atmosphere gets really intense since it is completely against her character. An example would be her envious side when she gets the feeling, Mio ignores her and spends instead more time with others like Nodoka Manabe. However, this out of character behavior was due to a fever she had at the time. Despite her mostly immature behavior, she has in fact common sense, especially when her unreliable teacher Sawako is around.
Ritsu's hair color is between dirty blonde-light brown that slightly touches the edge of her shirt's collar, her bangs pulled back with a yellow hairband. Two longer locks of hair fall at the ends of her hairband and touch her shoulders. She has hazel eyes, similar to her hair.
Without her hairband, Ritsu's bangs could reach her nose. Other than yellow, Ritsu wears other colored hairbands once in a while, such as white, black or red (especially when she was a child). At certain points in the anime, Ritsu uses other objects to hold her hair up, like goggles when the girls visited the beach or when she put it up in a ponytail that stuck up when she was about to sleep during a field trip.
In the manga, Ritsu does button her blazer, yet, like in the anime, she does not tuck in her uniform when seen without it. Besides her school uniform, she is often seen in polo shirts.
Her school uniform is often untucked (only tucked in by force, such as when Sawako forced her to or for official purposes like the graduation ceremony or the graduation photo) and her blazer is unbuttoned. She is the only one from the Light Music Club that does not wear the beige waistcoat that is part of the summer school uniform and is instead only wearing her white blouse. Ritsu is seen wearing the school's blue tracksuits most often among her friends, mostly when she plays the drums. She had once exclaimed that she prefers wearing comfortable clothing than any other outfits as she had difficulty drumming in those clothes. Like in the manga, she is often seen in polo shirts outside of school.