The following is an unofficial transcription and translation for SENPAI, provided by hongfire user Shani Andras. The timestamps provided were marked by james622; they assume a continuous video, as opposed to the official distribution that breaks the video into segments. Additionally, bracketed dialogue is for Shinnosuke's full-screen overlay lines, as he does not have a voice actor in SENPAI.
[0:12] Tendo: Senpai!
[0:15] Tendo: Senpai! You made it.
[0:20] Tendo: Thank you very much!
[0:22] Tendo: Then, you can hang together with us right?
[0:25] [Well, yeah but..."with us"?]
[0:29] Tendo: That's great! Manami, Senpai says it's ok
[0:32] Manami: Oh...wow
Title Card: Senpai
[0:47] Manami: Senpai, Senpai do you like it? Senpai...
[0:57] Tendo: Senpai's dick is huge, it's amazing!
[1:13] Manami: Senpai...
[2:07] Tendo: Senpai, you already came!
[2:55] Manami: Senpai, you're so kinky.
[3:02] Tendo: Manami, your tits are so lewd!
[3:09] Manami: Stop, i'm starting to feel weird!
[3:21] Manami: Senpai's dick is trembling.
[3:24] Tendo: Manami, you want it in don't you?
[3:31] Manami: Yes, is it ok?
[3:35] Manami: Senpai...
[3:43] Tendo: Amazing.
[4:03] Manami: It hurts! No!
[4:22] Tendo: Amazing!
[5:10] Tendo: Senpai, you can still going right?
[5:40] Tendo: Senpai!
[6:07] Tendo: The tip of your dick!
[6:19] Tendo: So good!
[6:28] Tendo: It-It feels so good!
[6:40] Tendo: I’m cumming! I'm cumming already Senpai!
[7:00] Manami: As expected, he is still hard.
[7:04] Tendo: It seems he can still do it.
[7:05] [No...i'm done already...]
[7:16] Tendo: Senpai, does it feel good?
[7:22] Manami: The tip of your dick...it's so hard right now!
[7:54] Manami: Senpai, your dick is amazing.
[8:00] Tendo: Amazing!
[8:02] Tendo: Senpai, i still want more...
[8:07] Manami: You're so mean Ayane, it was supposed to be my turn next!
[8:11] Tendo: You snooze, you lose!
[8:24] Tendo: Senpai!
[8:31] Tendo: So-So good!
[8:37] Tendo: No-No!
[8:43] Tendo: So good!
[8:48] Tendo: So good!
[8:52] Tendo: Senpai!
[8:57] Tendo: I’m cumming already!
[9:15] Manami: I still want you, Senpai...
[9:43] Manami: Senpai!
[10:07] Manami: No-No!
[10:20] Manami: Senpai! Senpai!
[10:44] Tendo: Senpai, thank you very much for today!
[10:48] Manami: Senpai, it was incredible...
[10:56] [Don't mention it...]
[10:58] Tendo: Hey Manami, who do we choose for next time?
[11:02] Manami: How about Kamiya-senpai?
[11:06] Tendo: Eh? really? I'm interested in him as well.
[11:10] Manami: Should we go for him now?
[11:11] Tendo: Now? I can't believe it, you still want to do it after all that?
[11:16] Manami: I didn't say i still wanted to do it
[11:18] Tendo: Yeah, i see, anyway, shall we go now?
[11:23] Manami: Stop making fun of me
[11:25] Tendo: Ah, senpai, let's do it again another time!