"Just Because" ending from the light novel adaptation, right after the "dame" scene, summarized by Cinnamon.
Eita agrees to go with Ena on a date to Enoshima since she wants to thank him for the picture. He meets Mio on the same day by the station. She asks where he is going, which he tries to not answer, she asks him if he was going on a date with Ena, and he thinks she may know about it. Ena comes, they sit in the same wagon. Mio on the other side. Mio later goes off to the beach, crying while smiling after Ena and Mio subtly talk with each other while Eita goes “what are you talking about?”
Ena and Eita arrives at Enoshima and climbs up where she takes pictures. The present she gave him was a photo album. With pictures of Hiroto, Yoriko, Hazuki from their time at high school, a time without him. She asks whether he wanted to be in those pictures. She says that she will confess to him if she wins the award and runs away. This scene was my favorite of the whole novel.
Mio meets Hazuki after one of her preparation classes. Hazuki asks whether Mio has any feelings for Hiroto. Mio says she had a first crush which she never did anything with. No progression, nothing. She ends with that she had found a proper one now.
Eita has been running and practising his form for a while now. The day before the entrance exam for Jouei. He meets with Hiroto, Hiroto talks about Hazuki rejecting him. Then how she confesses to him. In short, they are going to be busy with their new jobs and lives. Going for a long-distance relationship where he visits her from time to time. Hiroto asks whether Eita is taking the entrance exam tomorrow. Hiroto is frustrated since he didn’t know about it, he heard it from Ena.
On the way back Ena meets with Mina who drives him home. They talk about how Mio is not faking her reactions when together with him. He tells her he is taking the entrance exam for Jouei.
Mina tells Mio she met him later and tells her he is taking the entrance exam for Jouei like her. In their group chat before going to bet, everyone is encouraging her.
Eita goes to the entrance exam location early to not meet her since he hasn’t told her and it would be awkward.
On the graduation day, the greets the vice-principal and while everyone else are taking pictures and enjoying their last moments together, he goes to the photography club to meet Ena. There is a gold award on the desk. Their club won’t be disbanded. Her name is not on the award, but one of her senpais who took a photo of her when he took a photo of Eita and Hiroto.
Eita wants to give her a proper answer and says he has been in love with a girl since long ago, sorry. She cries a bit but smiles in the end.
After almost everyone has left, he goes to the sports field. Mio sent a message and wants them to meet at the hill behind their middle school. He meets with Hiroto. He asks whether he hasn’t gone to her. Eita says he hasn’t won yet. Hiroto wonder a bit, but then they go the the baseball field. Hiroto takes the pitching glove from Eita and gives him the bat. Hiroto is a real bro.
After that scene, he sends a message to Mio that he would be late, but she hasn’t seen it. When he comes later, she was not there anymore.
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Since then he has been looking for her at the university, on the station, in the mall. His message to her hasn’t been read either. He meets up with his friend from Fukuouka. He feels a slight regret that he wasn’t able to meet her again. During a break he wanders off and randomly walks on the campus, arriving at a park with cherry fields on either side of the road. He takes a picture and realising he has nobody to share it with. He takes up his phone and looks at Mio’s page. Suddenly “Seen” was added to his message and he is so surprised he almost drops his phone. He asks whether how her university life was, she asks the same back. She sends him a picture of a cherry trees in the background. There was also a university student with his bag, his uniform on it. He turns around and sees her smiling, having done a prank on him. He then tells her what he had been wanting to tell her all along.