Since you're already leaning to Sakura anyway: she has a personal mission with personalized earrings as well. The earrings are better than the regular earrings you get from equipment gachas, but still not as good as a leveled +10 ring. So it's awesome to unlock her personal mission and get those earrings, but if you're OCD, that will also create a strong urge to somehow unlock her second equipment slot to actually equip those earrings xD.