New girl goes to a new city and have problems making friends.
Find out about the senpai that's really popular and takes care of an aquarium
Realize the girl is actually as lonely as her and becomes her friend

a little like Amanchu, except for the fact that the author is actually trying to ship both girls together.

http://comic-walker.com/contents/detail/KDCW_AM01100045010000_68/