Tomoe is a third year student of Aiho school. She is a member of the student council, has been elected class representative, and she also volunteers to help with the school library. Tomoe owns a pet cat Toshibo. She is able to communicate with it to some degree. Tomoe's family owns an inn with a hot spring, Hotel Katsuragi, in town which Asumi uses as their meeting place.
Tomoe is very hard-working, honest, and timid. She is quite popular at school and Kosuke revealed that there exists a fan club at the school dedicated to her. Tomoe is polite and refers to everyone by their last name. She also cracks easily under pressure and falls ill with fever when stressed.
First Year of High School
Detailed in Episode 19: Then the Three Meet.
Tomoe found Asumi to be very loud and pushy. Every time Asumi raised her voice, Tomoe would quickly apologize and Marumu would act indifferent. Tomoe found it easier to relate to Marumu. Some time later, Tomoe requested Yagami for a transfer to a different room. Yagami assured her that she would be good friends with Asumi.
One day, Asumi decided to fight Tomoe and Marumu to decide their leader. Asumi, satisfied with the fight, gave them yellow colored hair ornaments as a sign of friendship, explaining that yellow is the color of happiness. Tomoe received a yellow scarf that she wore on her head since then.
Heart de Roommate
Episode 1: The Beginning
When Asumi brought Yusuke to their dorm room, Tomoe disapproved of her decision, reminding her that the Harukaze girls' dormitory disallowed boys. Tomoe was wary of Yusuke.
Episode 2: Transformation
Asumi helped dress Yusuke up as a girl for him to travel between the dorm and school.
Episode 3: The Name is Toshibo
Tomoe rescued Toshibo from Asumi and fed it to excess. Tomoe explained how she took Toshibo as her pet. Asumi accepted it into their circle of friends and called it "Parasite 2".
Episode 10: The Baseball Fanatics
Akane, Kaoru, and Midori announced to Asumi that Namiki had joined their team. Kaoru mocked Tomoe and Marumu attacked them. Tomoe fell ill with fever and she was frustrated by her weakness. Yusuke followed her out the dorm room and she announced that she will practice.
Tomoe struggled to bat and Akane and her friends mocked her. Namiki defended Tomoe. That night, Tomoe continued practicing with Toshibo outside the dorm. Asumi explained that they had been doing that for 3 nights.
During game day, Namiki was pitcher. She purposely threw 4 balls to get Tomoe into the game. Namiki struck her out twice. Toshibo then appeared to yell to her when to swing. Tomoe managed to hit a foul ball and Asumi called for a celebration at the Okonomidama okonomiyaki restaurant.
Episode 12: Shaking Heart: Part 1
Yusuke volunteered to help Tomoe return books to the library. She assumed that he liked Asumi. Yusuke tried to explain but she fell on him and accidentally kissed him. Tomoe was stunned and ran away. Yusuke chased her to apologize but she slapped him and ran.
The next day, she refused to leave her room while Yusuke was at the dorm. That night, Tomoe made dinner but refused to make eye contact with Yusuke.
Episode 13: Shaking Heart: Part 2
Yusuke was walking to the dorm with Tomoe. He apologized for the accident. Namiki offered to console Yusuke and assumed that he had confessed to her. He explained that he hasn't and she sent him to do so.
The next day, Yusuke waited for Tomoe at the school gates. Tomoe tried to avoid him but he begged her to listen. Yusuke confessed his feelings for Tomoe and she listened silently. Yusuke then ran away. That night, Tomoe approached Yusuke at his closet and confessed her feelings.
Tomoe wasn't able to find private time with Yusuke for the following days. She decided to invite Yusuke to her family's inn under the pretense of another one of Asumi's meetings.
Episode 15: A New Semester & A Transfer Student
Yusuke returned home for the summer break. He and Tomoe has been exchanging letters. When Yusuke returned to the dorm, Tomoe welcomed him. Marumu returned during dinner and Asumi arrived late for class the next morning.
Yoshiko introduced a new student, Hikaru. She refused to introduce herself and sat down quietly. She also avoided contact with the other students.
Yusuke waited for the girls at the school gates. Tomoe suspected that Asumi may have feelings for Yusuke. Back at the dorm, Namiki dragged Yusuke to her room. Namiki explained that Tomoe had confided in her regarding Yusuke and she supported Yusuke's relationship with Tomoe.
The following day, Yusuke invited Tomoe to further their studies to the same college. Tomoe explained that her family is having trouble with the inn and she may have to help them after she has graduated.
Episode 16: Love Storm
Yusuke, Asumi, Tomoe, Marumu, Namiki, and Toshibo were at the Hotel Katsuragi hot spring. Tomoe moved to sit beside Yusuke causing Asumi and Namiki to be surprised at Tomoe's bold move. Tomoe also noted that she is interested in Misaki.
At school, Yusuke witnessed Misaki talking to Tomoe. He demanded that Tomoe explain what they were talking about but she couldn't answer and ran away. Yusuke noticed that she had been spending more time with Misaki and heard rumors that Tomoe had feelings for him.
Yusuke then decided to confront Misaki after school. Yusuke was wearing the girl's uniform and Misaki confessed his feelings for him. Back at the dorm, Asumi explained that Misaki had been asking Tomoe about Yusuke. She also explained that Misaki had asked her about Yusuke before the summer break. Tomoe thought that his having a relationship with Misaki would be interesting.
Some time later, Yusuke left the men's restroom in his girl's uniform and bumped into Misaki. Yusuke then decided to explain his situation on the school rooftop. Misaki was shocked and apologized to him. A week has gone by and there were no rumors. Tomoe was happy that the ordeal was over. They both expressed their worries that they may lose each other if there was a rival.
Episode 17: One Fine Weeked
Tomoe invited Yusuke to Hotel Katsuragi. She explained that she has to attend a family meeting. Takuto later joined their meeting. The meeting lasted until night and Tomomi invited Yusuke to stay for the night. Yusuke and Tomoe returned to the dorm the next morning.
Yusuke asked Tomoe about the topic of the meeting. Tomoe didn't answer, but instead asked Yusuke what he thought was more important, one's self or one's family. Yusuke answered that both are equally as important. During dinner that night, Tomoe announced her relationship with Yusuke to Asumi and Marumu.
Episode 20: The First Arranged Marriage Meeting
Yusuke followed Tomoe out of the dorm late at night. She revealed that she has been arranged to get married and that she was unable to satisfy both her own desire and her family's needs. They went to Hotel Katsuragi the next day. She explained that she had placed her family's well-being over her own; that her parents had arranged for her to be married to her cousin Takuto
(Detailed in Asumi's and Marumu's path) Tomomi explained that Tomoe and Takuto were childhood friends. Both their parents are hotel owners. They dated during junior high but later broke up. Hotel Katsuragi has been doing badly during the recession. Tomomi requested for help from the hotel association and Takuto was the chairman. He proposed marriage to merge their hotels.
The next day, Yusuke, Asumi, and Marumu tried and failed to interfere with Takuto. Tomoe appeared and explained that she no longer loved Takuto. Tomomi requested him to call off the marriage.
Tomoe explained that her love for Takuto helped her gain confidence. One day, she discovered that he was dating another girl at the same time. She phoned Takuto to ask about his true feelings and waited for his return in the snow. Takuto never showed up and Tomoe gave up.
She was thankful for Yusuke, Asumi, and Marumu for helping her family and her gaining confidence. Yusuke also thanked Tomoe for helping him gain confidence as well.
On the way back to the dorm, they met Takuto. He revealed that he had approved a loan to Hotel Katsuragi. On Asumi's path, it was revealed that Namiki found a new boyfriend in Takuto and she convinced him to help Hotel Katsuragi, arguing that if he truly loved Tomoe, that was the right thing to do.
Episode 23: Fading Friendships
Marumu offered Hikaru a handmade yellow pin. Hikaru slapped it out of Marumu's hand and Asumi advised Hikaru to run away from class.
That night, Tomoe confronted Asumi, demanding the reason as to why Asumi defended Hikaru instead of Marumu. Asumi ordered Tomoe to leave her alone. Tomoe thought that she was a burden to Asumi. She voiced her suspicion that Asumi had feelings for Yusuke and she wanted Asumi to tell her the truth. Tomoe was upset that Asumi didn't trust her enough as a friend. Asumi then slapped Tomoe, declaring that Tomoe was too kind and that there exist problems that cannot be solved with kindness alone.
Episode 24: Harmony of Minds
Yusuke bumped into Asumi. She told him to forget what Tomoe had said and took the blame for the fight. He relayed Asumi's message to Tomoe and she shared the blame. Tomoe predicted that she would have given up on Yusuke once Asumi had revealed her feelings for him.
Yusuke identified Hikaru as the source of the conflect between Asumi and Tomoe and decided to confront her. He discovered Asumi and Hikaru on the school rooftop. Asumi explained Hikaru's past to him. Yusuke relayed Hikaru's story to Tomoe and Marumu. They decided to help Asumi befriend Hikaru. That night, they declared their intent and repaired their friendship.
The next day, Yusuke discovered Hikaru on the school rooftop. Hikaru stripped naked and demanded sex from Yusuke, declaring that anyone who touches her will only get hurt. Yusuke noticed a cut on Hikaru's wrist and declared that he will not betray Tomoe and left. Rumors spread about Yusuke and Hikaru on the rooftop. Tomoe confronted Yusuke about it and he told her the truth. Tomoe accepted it. Asumi had also heard the rumor and attacked Yusuke. Tomoe explained the situation and she voiced her support for their relationship.
The following day, Yusuke and Tomoe found Hikaru in town. Tomoe confronted Hikaru and she revealed that she doesn't want to return home. The next day, Yusuke and the girls dragged Hikaru to the Harukaze dorm. Asumi declared that Hikaru will be staying with them from then on and Yagami revealed that Hikaru's lodgings had already been officially registered. Hikaru was assigned to Namiki's room.
Episode 25: Our Bright Youth
On graduation day, Hikaru was nowhere to be seen. Toshibo reported to Yusuke and Tomoe that Hikaru was at the park. Hikaru explained that her existence only hurt others and she was afraid of graduating and facing the outside world. Asumi shared her insecurities with Hikaru and her resolve to never give up. She also declared that Hikaru had already found the most important thing in life, friends. Hikaru broke down and returned to school.
They had missed the graduation ceremony. Yagami was upset but Hikaru voiced her desire to graduate with her classmates. Yagami then led them to the schoolyard where their classmates were waiting for them.Tomoe and Yusuke made a pinkie promise to never forget each other.
Final Episode: Roommates Forever
Yusuke and Tomoe met during their one year anniversary. They had lost most of their feelings for each other. Yusuke had been studying for an entrance exam for a university in Tokyo and was accepted in Spring. Tomoe had been helping at Hotel Katsuragi and attending a local university.
Marumu later appeared but Asumi didn't. Yusuke explained that Asumi had furthered her studies to Greenland and left instructions to watch a video tape if she couldn't make it. Yusuke phoned Yagami for help and she brought them to their old dorm room to watch the tape.
The tape was recorded soon after Asumi left Aiho school. She apologized for not being there. Asumi thanked them for their time with her. She explained that she liked Tomoe's personality and apologized for their fight. Asumi also told Yusuke to never let go of Tomoe.
Yusuke then returned the dorm room key to Yagami. When Yusuke was just about to leave, he and Tomoe rediscovered their feelings for each other. They promised to see each other again and to re-ignite their passion for each other.