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- Sadamatsu came from Minatogawa family, a family which known to have their own style in arranging flowers, Minatogawa-ryuu. Not much known for Sadamatsu's past except he was really fond of Miracle Man, back in his childhood days. He also collected plushies and seemed he couldn't spell his name right, as he named them as "Property of Sadamashi Minatogawa". At some point, he attended Mikagura Academy and had been joined flower arranging club ever since. He also became a representative of said club and his power was awakened there. Since there was no much people who took an interest in flower arranging, not to mention that members were decreasing in each academic year, now he became the sole member of flower arranging club. Due to this, he was really longing for a new club member and friend as he almost always spent his time alone on the clubroom.
Stride After SchoolEdit
- As a club representative, Sadamatsu took a part in freshman party by performing his ability, which is blooming flower in such a short time, and sat on it, made Eruna Ichinomiya who was watching him from afar shocked. He seemed lonely on said event and Himi decided to tease him by surprising him from behind. However, being calm as always, he responded to it albeit in a low tension manner, made Himi Yasaka wondered that was he really surprised or not.
- Some days later after the freshman party, Eruna came to his clubroom, attempted to join his club. Sadamatsu was really delighted to hear that and he asked her first whether Eruna likes flowers or not. When Eruna responded that she knows nothing about flowers, Sadamatsu replied that it was no big deal as he would be the one to teach her about flowers personally. However, before truly becoming a flower-arranging club member, she had to past seiza test for at least three minutes. Alas, she failed in the first minute. This made Sadamatsu slightly disappointed as he was about to welcome her to his club.
Spiritless Coup d'EtatEdit
- Sadamatsu was seen beside Seisa Mikagura, in the corner of the open space in Rookie Battle Tournament technical meeting day. Seeing Seisa who watched Eruna in an amusement, made Sadamatsu wondered and asked her about why she did not let Eruna to join her club. However, Seisa responded his question by saying that Eruna has 'something' that she eager to see how it develops.
- Sadamatsu opened a shooting booth alone in Rookie Battle day. However, it did not went well as he couldn't invite any customer and couldn't smile properly. This made Eruna decided to help him, and when she thought that Sadamatsu must be feel lonely due to troubled face he made, it was actually because he had to go to toilet and did not know what to do. Eruna's help saved him anyway, as he left the booth to Eruna. Although there was no people who came to said booth, however Yuto Akama took an interest on it and tried to shoot the grand prize, which was a giant Miracle Man doll. But, no matter how much he shooted it, the prize was standing still. Later, it was revealed that Sadamatsu was actually putting a trick behind it as he did not want it to be given to anyone, yet he made it as a grand prize.
- He, along with Yuto, explained to Eruna about club budget and how to obtain it. He also told Eruna that it is not good to use club budget for one personal purpose. Before Eruna left, Sadamatsu gave some support to her by doing the thumb up, which was also responded in a same manner by her.
- In the night of same day, Sadamatsu was invited by Shigure to came to a small party for congratulating Eruna. Sadamatsu, along with Yuto, Himi, Asuhi, and Katai decided to surprised Eruna by hiding behind a curtain and said a congratulation at the same time after the signal came. He enjoyed the party by hearing other stories, though he was quite bothered by the fact that Himi was drunk and attempted to undress herself in front of him. Gladly, it was stopped by Katai.
- Sadamatsu came to Eruna's preliminary battle, a battle of her and Haruka Toishi. However, he only could gave her a pokerface on her loss.
Seeing a Sixteen-day-old MoonEdit
- Sadamatsu watched the final battle of Asuhi vs. Otone Fujishiro. After Otone was announced as the winner, Shigure quickly came to interview her for a Hero Interview. However, due to not wearing any glasses at times, he asked and gave the microphone to Sadamatsu instead, made Sadamatsu slightly happy and even answered the question which actually was not intended for him in a delighted manner. Upon hearing Sadamatsu's voice and realized that he interviewed wrong person, Shigure dodged the question to Otone. This made Sadamatsu slightly disappointed and bite his handkerchief in process, made Eruna wondered that was he really want to be interviewed that bad.
- Sadamatsu also participated on Treasure Hunt Event by delivering some hot tea. However, he prepared to much tea and decided to drink it by himself once it got started to be cold.
- Sadamatsu was also the one who took care of flowers in the Academy, though sometimes Otone did the same too. When Eruna came to his clubroom to introduce Otone, he actually had known about her since the flowers told him that sometimes Otone also taking care about them too. Otone responded him in a slighly tsundere way, as she said that there is no way she would join the flower arranging club, but Sadamatsu responded that despite knowing it, feel free to come to his clubroom if she likes to take care flowers.
- Sadamatsu came along with Kyoma to Eruna's club room to give the girls congratulatory present. When Eruna asked for his help to mediate the misunderstood between Kyoma and Otone, Sadamatsu were chatting with Himi while sitting on the zabuton, unconsciously ignoring Otone, Kyoma, and Eruna. In the end, he dragged Kyoma to outside to calm himself down.
When it was finally his turn to give the present, Sadamatsu was really excited. He bloomed the forget-me-not flowers around the corner of the room. He said that the meaning behind the flowers were "don't forget me", which suddenly made the room filled by heavy aura. However Sadamatsu then said that it was actually just a joke and asked everyone whether they were surprised or not, albeit with poker face and monotonous tone. He then gave the girls the real present by bought back the forget-me-not flowers down to earth and replacing it by blooming lupine flowers instead, and explained that the meaning behind the flowers were "numerous friends to come", hoping that there would be many student who would like to join Eruna's club.
- On the Midterm Battle, Sadamatsu was appointed to fight against Himi in a bamboo forest arena. Before the battle began, they settled a deal that if Sadamatsu lose, he should treat Himi any snack she wanted but if he win, Himi should treat him a candy apple. The battle started and Sadamatsu succeeded to crush two of Himi crystals while hiding himself behind the flowers. The battle lasted for quite a long time and when Himi about to crush his crystals, Sadamatsu revealed and activated his ability, Selfish Flower, made him win in the process. After the battle was over, they returned and Sadamatsu asked Himi to treat not only him, but also the others the candy apple, which was rejected by Himi as Himi would treat Sadamatsu only, as in the deal.