本気になってないよね is a Weiß Schwarz card from 彼女、お借りします Vol.2 KNK/W132-014. Compare listings from Singapore Weiß Schwarz sellers on CardJio, then jio them on WhatsApp.
【CONT】 All of your characters get +1000 power and +1 soul. ([[bounce.gif]]: When this card triggers, you may choose one of your opponent's characters, and return it to your opponent's hand.)