Sometimes, in anime, the young protagonist is mean to his little sister. When that happens, the sister demands payback, often in the form of a monstrously huge and/or unbearably adorable parfait/sundae. Generally when she gets the treat, it sparkles and there’s a magical tinkly sound.
Walking around Sunshine City in Ikebukuro, we found a place called the St. Marc Café. Magical parfait sundae? Nailed it.