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.

Peko tries her best to fight against the effects the sexy soup has on her when she notices Fuyuhiko struggling with Kazuichi, but she's unable to fight back any longer once Mikan practically tackles her in a hug and keeping her body pressed up against Peko. For the first line, Peko is slightly breathless from the effects of the sexy soup, but she's determined to go help Fuyuhiko. For the second line, she's shocked and slightly flustered by the extremely suggestive comment Mikan made about her sword. For the third line, she's extremely embarrassed and flustered by all the suggestive comments Mikan continues to say and is unable to even finish her sentence.

Peko should be voiced by a female with a mid-low vocal range. Personally, I prefer her game voice over her anime voice so I'll be looking for voices that more closely resemble that. Exact voice impressions aren't at all mandatory, but I do want a voice that stays true to her character.

Voice reference:

https://www.youtube.com/watch?v=urg5zFsp6Xg&t=21s