Just go see for yourself, Chihaya overcoming the trauma that tormented her for years, with the help of her friends.To wit After refusing Haruka after the umpteenth time, they send her an original lyric for her to sing. Gathering her courage, she returned to the concert just in time to sing, but then she realized that her voice still won't come out due to still not overcoming that past. Just before Ritsuko pulled the plug, the whole 765 Pro idols come in and sing the first part of the song, until Chihaya gathers enough courage to get over her past and her voice is restored. There's a reason why people claim that Manly Tears were aplenty during that episode.
Episode 24, aside of Tear Jerker and mainly Haruka regaining her composure (which is pretty heartwarming), and the 765 Pro saying that they're waiting for the New Year concert (most heartwarming), there's another when Miki returned and stated she's offered the position of solo emcee of the successor of "Are We Live?". Knowing the hypercompetitive Miki who's always looking out for the top... you'd expect her to accept, but then she refused just for the sake of Haruka (saying she might get lost if she accepts).
Episode 13, when the RGKM runs to the camarin after their show is over only to get a picture of all the girls sleeping soundly.
The 7th Anniversary Live concert. Just thinking about a franchise that started in arcades, that was the first job for most of the girls, has grown into something that's lasted so long.
A standout as Asami Imai performs Yakusoku - and the audience all raise blue glowsticks: Chihaya's color. She's actually moved to tears by the support and love from the audience. And when she sings about walking along with friends, the rest of the 765 girls are silhouetted on stage behind her, in the poses from the title screen.
Something of note is her blog entry, translated here. She talks about how important and personal iDOLM@STER, and especially Chihaya, have become for her, and how grateful she is for being part of it. She brings up the performance itself, and how after the performance, the other girls told her what they were feeling behind that curtain.
"I sang 「約束」 with you!"
"I was crying while standing behind you."
Maya-chan told me while crying, "You were amazing!!"☆