From Aerandria Scans:
Satoshi and Satomi are childhood friends who have been trying to outdo each other in everything since they were small. Christmas is coming, and they’ve started a new challenge to see who can get a date for Christmas first! It seems that Satoshi might win the bet, with Natsuki-chan, the Sexy Dynamite of the class making the move and asking him to be her date, but will things be that simple for our plain-looking boy?

Extra oneshot from Otomentaru.