What's so confusing? It's pretty plain and simple. Mihashi has a doppelganger whom he consider his only friend. All of the sudden, his teammates were able to see his doppelganger His doppelganger was everything that Mihashi wasn't and when Mihashi overheard Abe's conversation. He thought he was no longer needed and wanted the doppelganger to replace him. So, the doppelganger takes his place which made everyone except Abe forget. Abe searches for Mihashi and found him at home. He was somewhat able to convinced Mihadhi and went back to the baseball ground and doppelganger was forgotten and disappeared because Mihashi no longer needed doppelganger. At least that was the overall understanding I had of the manga. This is an anime by the way, so the manga is just a fanart
Can someone explain to me what just happened? I'm literally a little confused.