In this scene of the anime, Hiyoko has basically drugged everyone with Teruteru's aphrodisiac soup so all the characters are all hot and bothered and not acting how they normally do. Please refer to the video in the casting call's description for more details.

Despite also being under the effects of the sexy soup, Fuyuhiko tries his best to stop Kazuichi from doing anything to Sonia. In the first line, he's rushing up to Kazuichi who's beginning to unzip his clothes in an attempt to get him to stop. In the second line, he's trying to get Kazuichi to snap out of his daze while also doing his best to fight against whatever effect the sexy soup is having on him. In the third line, he's getting frustrated at Kazuichi's persistence and trying to get him to stop unzipping his own zipper so Fuyuhiko can finally zip it back up for him.

Fuyuhiko should be voiced by a male with a mid-range or deep-range voice depending on which of his voices you'd rather use; his anime or game voice. I personally like both so I have no preference. Exact voice impressions aren't at all mandatory, but I do want a voice that stays true to his character.

Voice reference:

https://www.youtube.com/watch?v=L-xMx4NQSoM