You're likely to succeed if you try

On a non-specific, not overly nice but very much decent summer day, Fu witnesses Yuna and Tougou going on what appears to be a date. Knowing that Itsuki is occupied, she calls who has to be called and with few words and even fewer explanations, Karin is summoned to her side via the force of text messaging to help Fu in her quest for the truth. Series of Oneshots.