Haruka's younger sister, She initially sees both Takayuki and Mitsuki as older siblings until she finds out they have been seeing each other behind Haruka's back. While Haruka is in the hospital, she visits every day since there is no one else that can keep her company, even if Haruka is in a coma. This shows just how much she loves her older sister. She, like Mitsuki, is a powerful swimmer in her own right, but feels as if she can never match Mitsuki. Her intense hatred towards Mitsuki after the accident can be attributed to the feeling of personal betrayal by someone she considered an idol for throwing away her (Mitsuki's) talent and dreams as well as Mitsuki's betrayal of her sister by her sexual relationship with Takayuki. She learns to move on in life and becomes a top swimmer in Japan. (Source: Wikipedia)
Very young student (10 years old in the beginning) in Nodame's school in Paris. His goal is to be a conductor. In OVA 2, he became 15 years old and is in love with Chiaki's cousin, Yuiko.
Mitsuki is friends with both Takayuki and Haruka, but secretly she has feelings for Takayuki. In high school she was a competitive swimmer, but shortly after Haruka's accident, she finds herself leaving swimming to tend to Takayuki. She throws herself at Takayuki when he fails to climb out of his depression, and reveals her feelings for him. Mitsuki is well-meaning, but suppresses her feelings, allowing them to bottle up and explode in dangerous ways. Mitsuki also believes that she is responsible for her friend's accident, as she was the main reason why Takayuki was late for his date with Haruka. (Source: Wikipedia)
A robot built for war who wishes only to improve his skills at piano and serve his aged master with the greatest of loyalty.
Number 2. is a member of the FAKE KNIFE and the brother of Number 1. He loves intestines, however, he is deeply afraid of blood. He is rather weak mentally.
Tsugumi is a hitwoman who was raised and trained by Claude of the Beehive Gangsters.Tsugumi is originally introduced as a guy who transfers to Chitoge's class, and has orders to protect her from Raku, whom she thinks forced Chitoge into the relationship. She and Chitoge are childhood friends; she tries to keep a ten year old promise of becoming strong to protect Chitoge. However, after Raku treats her nicely, she begins to develop some feelings for him, even though she is too stubborn and embarrassed to admit it. In America, her assassin code name is "Black Tiger," who had a rivalry with "White Fang." She does well academically, having ranked next to Chitoge on a yearly exam. Later when she learns that Chitoge and Raku had been having a fake relationship from the start for the reason of only to stop their families from fighting. She investigates their individual feelings for each other to know if she has a chance. She comes to the conclusion to give up in order for Chitoge to be happy and one day when alone with Raku in the classroom, she places her hands over his ears and confesses her love so that he doesn't hear it. She later helps Chitoge and Raku come to terms to their mutual feelings. In the epilogue, she becomes Chitoge's exclusive model. (Source: Wikipedia)