Sparkler Heaven is the fifth stage in Summer Diary.
Drummer Doge spawns shortly after the stage begins, freezing some of your cats for a second. It continues to freeze your cats every 5-10 seconds. Doges, Doge Darks, Gorys will then spawn. A minute into the battle, Gory Blacks will be sent out and backed up by several Gorys.
You can bring along some Anti-Black Cats (Flower Cat, Tin Cat, Weightlifter Cat) to deal with the Dark Doges and Gory Blacks. A stack of Paris Cats, more often than not, is enough to keep pushing back the Black enemy units. Just remember to protect your Paris Cats with your meatshields.