High School Girls (also known as Girl's High) is a manga series, created by Towa Oshima. It ran from 2001 to 2006. It also received an anime adaptation.
Love, Deception, and a Love Hotel? (E03)
Eriko appears as a fat detective.
Long Ago, We Were Young Too (E08)
Eriko and Yuma participate in a ramen-eating contest.
A flashback shows Himeji when she used to be fat.