I’ve found a comedy horror manga that has a fat female protagonists: Hisako Omori aka 大森久子 from Bizarre large serving!! Nikuko-chan (Collection of works by Miyako Kojima) aka 怪奇大盛!!肉子ちゃん (児嶋都作品集)
Hisako Omori is a very pure and adorable girl ... a little too "healthy" than usual ...
A mysterious laughing school gag horror over a meat child with a hellish stomach that really eats everything regardless of likes and dislikes! !!
"It's not a flesh, it's a similar Hisako !!"
The first volume of the serialized work of Kadokawa Shoten "The Horror".
Complete recording of extra color change and sugoroku at the time of publication!
It’s ran two volumes.
http://hangyo.sakura.ne.jp/miyako/mibook.htm