Atsumu "Yukiatsu" Matsuyuki is the main antagonist in the anime/manga series, The Flower We Saw That Day.
Yukiatsu is a arrogant and manipulative 16-year old. He is also considered athletic, handsome, and intelligent, being able to accel at school and sports. For the majority of the series, he acts cold and condescending towards his former friends from his childhood, particularly Jinta. This stems from his unrequited love for Meiko, who evidently shows affection for Jinta. He usually carries a calm demeanor, but is easily agitated when the subject of Jinta and Meiko is brought up. Deep down, he is tormented by Meiko's death, which causes his obsessive and antisocial behavior, such as reminiscing about Meiko while breathing heavily into dress and manipulating his former friends into believing that Meiko returns as a ghost. Despite this, he does have a caring, allowing Anaru to confide in him, and willing to reconnect with his childhood friends while desperately trying to help Meiko pass on.
Yukiatsu is a childhood friend of Jinta, Meiko, Anaru, Chiriko, and Tetsudo. He harbors feelings for Meiko, and wants to confess to her, but she passed away. Throughout the series, he constantly antagonizes his former friends, mainly Jinta. Yukiatsu puts on a dress to attempt to fool his friends into believing that Meiko returns and that everyone can see her. He did this because he was jealous and agitated when Jinta confesses that he can see Meiko in ghost form. He is also caught in several arguments with Jinta, often taunting or ridiculing him.
He confides with Anaru because she is similar to him, suffering from unrequited love. Towards the end of the series, he finally accepts that Meiko has returned in ghost form, and opens up to his former friends. He collaborates with them in helping Meiko pass on, such as having a firework. Despite being prideful, Yukiatsu is willing to get down on his hands and knees and beg. After this plan fails, he is caught in another argument with the group, which led to everyone, including him, confess their vulnerability, which helps everyone understand one another, which helps Meiko pass on. Prior to passing on, Meiko left him a handwritten letter, which allows him to let go his anguish from losing her. At the end of the series, he is much closer to Chiriko.❤️❤️❤️❤️