Ritsu also clings onto Mio like a lifeline when it comes to studies, and claims that Mio is the best tutor she has ever met. There have been times when Mio clings onto Ritsu instead; when Mio was being bullied by Sawako or other people, Mio would come running to Ritsu hoping she would save her from distress (sometimes however, Ritsu might join in the bullying too). They both have a similar interest in photography, as Ritsu always brings a digital camera and Mio a film camera around. Ritsu was also the one who introduced music to Mio, and encouraged her to learn bass. It was their promise that they would form a band together, as the bassist and the drummer, since they were little.

Ritsu and Mio understood each other so well that they could easily imitate each other, and at the same time act as Romeo and Juliet for their school's festival performance. Ritsu is able to recognise Mio by the sound of her footsteps.

There were moments when Ritsu got jealous when Mio was spending more time hanging out with others than with her, resulting in a bitter conflict between them. however, such arguments do not last long.

During Mio's Fan Club Tea Party presentation, their other band members questioned if the slide show was about Ritsu or Mio. Ritsu claimed that those were her photo collections she had with Mio since they were little, therefore she had appeared in every single photo. Those photos showed how they grew up together as best friends.

Yui and Ritsu have a lot in common, such as their lazy and laid-back attitudes, reluctance towards learning (or school in general) and their need for fun. They also have a sweet tooth for Tsumugi's treats and are usually the band members who propose a break first. Yui sometimes gets disappointed when she finds out that Ritsu has also a reliable side, like when she does well on her exams or takes care of her drums.

Despite acting immature herself most of the time, Ritsu sometimes criticises Yui's odd behaviour or thoughts.

Mugi treasured her friendship with Ritsu very much as seen that she always enjoyed Ritsu's company. Being as observant and wise, Ritsu had brought Mugi to commoners' places like tuck shops and the arcade, as she knows that Mugi might not have visited those places before.

Ritsu had once said that even without Mio, she still has Mugi to tutor her in her studies, meaning she sees her as a very reliable person (unlike herself).

Ritsu was shocked and speechless when she first found out in a phone conversation with Azusa that Mugi's house had a housekeeper. She is often amazed by Mugi's life standard which differs so much from her own.

Azusa badmouthed once about Ritsu being a "lazy and irresponsible leader", although the latter does not seem to mind that comment. It was because of that comment that the two of them grew closer and even found out about Mugi's family wealth together. Azusa had praised Ritsu's cooking before, yet in the same episode, Azusa was the one who pointed out Ritsu's father's underwear in the living room.

Despite being often disappointed by the club president's irresponsibility, Azusa still held her respect and admiration over Ritsu and the band's coherent performances. When Azusa first mentioned that she is joining the Light Music Club, Ritsu had practically pounced over her. Ritsu and Yui had been scolded by Azusa numerous times when they were lazing around and procrastinating during their training sessions and training camps.

At the end of the series, Ritsu could be seen worried over Azusa being the only remaining member of the Ligh music club (although that would make her the club's president). Ritsu would act responsibly as the leader whenever the club needs to do something for their junior. The most memorable scenes were when Ritsu went all out trying to recruit freshmen for Azusa and when she initiated to perform for her when she was considering quitting the Light Music Club.