Hoshitani was assigned to cleaning duty in the Kao Council room at sunset. While cleaning, he finds a fallen photograph. Picking it up, he recognizes the people in it.
He sees a younger Haruto-san, a younger Hiragi, Sazanami, Yuzuriha, and Akatsuki, but the last person... He recognizes him as the high schooler he saw that rainy day even though he knows that person is supposed to be Otori-senpai.
Hoshitani stares at the photo for a few minutes. It was then that Hiragi walked in. Seeing Hoshitani staring at the photo, Hiragi freezes for a second before walking over to him.
"I believe that's mine," Hiragi says, getting Hoshitani's attention. Hoshitani simply nods at him before taking a brief look at the photo again.
Sighing, Hiragi asks, "Do you want to talk?" Hoshitani sadly smiles, "You know... I kind of already knew, somehow."
Hiragi looks at him confused, "Knew what?" Hoshitani keeps smiling, "That he was the one I was looking for all this time," he looks at Hiragi, "It took two years, but I finally found him."
"He wanted to tell you but," Hiragi tries to explain on his brother's behalf, but gets interrupted. "It's OK...really. I'm glad I found him but... I want him to tell me himself," Hoshitani smiles as his eyes sparkle, reflecting the light of the setting sun.
Hiragi sighs again then nods, "Very well." He hands Hiragi back the photo, "Take good care of this. It's important to you, right?"
Hiragi shows a small smile, "Thank you." Hoshitani nods before leaving, a soft smile on his face. Hiragi just sighs once more, shaking his head at his brother and kohai, at how ridiculous they're being, but he decides to let them do what they must.
Bonus:
He does decide, however, to text Otori about what just happened. Otori's response was shock, surprise, and then dread at how he'd now have to tell his kohai. Hiragi offered his support, but wanted Otori to get it over with.
When Otori decided to tell Hoshitani, Hiragi was nearby for moral support. Hiragi sees them talking, Otori being apologetic and Hoshitani being annoyed at him. Then, he sees Hoshitani sigh, and he seemed to forgive Otori. Otori smiles and they hug each other. Hiragi smiles, happy for them.
When Otori and Hoshitani walked over to him, Hoshitani smiles as he says, "Thank you, Hiragi-senpai." Hiragi smiles, 'You're welcome."
"Otori-senpai, I'll see you later," Hoshitani smiles as he pecks Otori on the cheek. Otori gets slightly flushed, "Uh... Sure."
Hoshitani giggles a bit, "Oh, and I make no promises of asking you to be my coach again in the future." "Wait, what?" Otori quickly asks before Hoshitani yells, "Bye!" and runs off.
Hiragi and Otori just stare in silence before Hiragi says, "Are you two...?" Otori answers, "Yes." Hiragi nods, "Good...but I have to ask, just what did you two talk about?"
Otori's silence at that was concerning before he said, "I'd rather not say." Hiragi nods slowly, "Alright."
From then on, Hoshitani and Otori's relationship progressed, Hiragi giving them an ear, advice, and confidentiality when needed.