They are Japnaese idol group "Momo Iro Clover Z".

Their passionate dance and paformance strikes right at the heart of  people who had absolutely no interest in general,young idole group.

 

"OBK App" means japanese app competition　"OBAKA App Competition", that is afforded to　most foolish app!

this girl is Athuko Maeda ,who was member of  Japanese famous idol group "AKB 48".

This logo imaged it of AKB 48.

So She Said "Let's make  foolish app with me! ".