It's Haruka Hoshikawa, the most beautiful girl in his class, waving her cell phone around, in a futile attempt to catch (in a literal sense) radio waves.
She is so technologically inept that Kanata goes over to her house to help set it up for her. However.......
"You know, I have an extra empty room."
Her mechanical ineptitude is just a pretense.
It seems that getting Kanata to come over is her actual true intention—!
A love comedy about living with a young lady who is good at temptation!
(Source: GA Bunko, translated)