(Picture left to right: Run, Touru, Yuuko, Nagi)
Touru likes Run. Run is a year older than Touru thus started high school a year before Touru.
Touru passed to get into Run's highschool and thus we have the non-existent story (so far) of their yuri life in high school.
Back when Touru went to Run's house to tell her she got into her school, Run entered Touru's room and found another friend of Run's (Yuuko) on Run's bed over her like they were kissing (but they weren't) thus Touru is constantly suspicious of Yuuko around Run.
Run is the typical vague bimbo anime character who may or may not realised that Touru likes her (not sure yet)
Touru is the violent type who intimidates and hits Yuuko all the time and protects Run
They look like grade schoolers - I guess for the usual reason that people who watch these shows want to dream of being grade school paedophiles ...
Ignoring that - the first episode was almost amusing - but I have no idea what the rest of the shows are going to be like nor how they will actually make it amusing without going 'Lucky Star' - I guess we'll see if it is actually worth watching ...