[In this scene Koichi is narrating the introduction of himself, he is in a very calm and almost cheerful tone]
It happened April of 1999, it was my first day of high school, and I was about to make two very bizarre friends. I was about to become a high schooler and I wondered what the others’d be like. In case you were wondering, my name’s Koichi Hirose, though I guess it’s not that important.

https://youtu.be/uKzA9pGWgJM?t=119

[In this scene, Koichi is being swooned by Yukako, and clearly Koichi is not happy about it as these lines are spoken in his thoughts]
As if yesterday wasn’t enough, this is definitive proof that Yukako Yamagishi is completely deranged. I’ve gotta put a stop to this, but if I take a bite, I’ll just validate her feelings, And if I refuse, she’ll kill me! What am I supposed to do?!

 https://youtu.be/lhXjwDyN8Jg?t=106

[In this scene Koichi is getting beaten by Yoshikage Kira and is a bloody mess, but seems to have discovered his name and is using what little bit of energy he has left to provoke Kira]
Hmmph... What do you know... Your name is Yoshikage Kira. You look surprised, all I did was say your name, Kira.

Don't tell me you've forgotten, you reimbursed the cafe. You couldn't have given me a better clue if I'd asked.

Yeah, believe me, I know all too well what's about to happen, but even so. If a pathetic bootlicker like me can figure out your name that easily. I guess you're not as tough as you seem to think you are, sure you might get away for the time being but you know what Kira? I bet your every thought is mocking you for letting a whiny brat unravel the mystery of your name, and if they aren't I'll do the honors for them. A mulling little highschooler just found you out! You're such a colossal dumbass! I'll be waiting for you on the other side you murder happy son of a bitch!

https://youtu.be/RpCSFwhBzqI?t=141