Under the Terms and Conditions of Use, Atelier801 states fraises are nonrefundable. You will be unable to issue a refund through Steam.
Terms and Conditions of Use said:
Atelier 801 SARL may charge fees to acquire certain Games items. To this end, Atelier 801 SARL may allow the purchase of in Games "credits" ("Fraise") that may be applied to the purchase of in Games items. Items purchasable in Fraise are not necessary to play to the Games and can be acquired for free. ANY APPLICABLE FRAISE, FEES AND OTHER CHARGES ARE PAYABLE IN ADVANCE AND ARE NON REFUNDABLE AND NONTRANSFERABLE, IN WHOLE OR IN PART, FOR ANY REASON. FRAISE HAVE NO MONETARY VALUE AND CANNOT BE REDEEMED FOR CASH.