There's an anime episode where the main character does a backflip, and then the scene changes to a portrait of her. It said she died after hitting her head on the corner of a table, and then she had an experience in heaven, but it was actually a dream...

This is from episode 16 of the anime Strawberry Marshmallow OVA.

It's a serialized work by Japanese manga artist ばらスィー in the monthly magazine Comic Densetsu Daioh, and was originally an irregular serialization of illustration submissions, a moe manga in which "cuteness is justice".

"Strawberry Marshmallow"

The story features five girls between the ages of 11 and 20, who observe the seemingly ordinary world through their eyes. It is performed as a one-shot unit drama.

The setting of the story is based on many real-life places and things: the main characters live in Hamamatsu City, Shizuoka Prefecture (the author's birthplace), Hamamatsu Station, Lake Satsume, a dairy farm that sells a brand of milk called "Muta-no-oishiki-milk", and the elementary school where Miu and the other four go to school. However, the weather in Hamamatsu is mild and snowfall is rare.

Shinie and Chika are sisters who are very close despite their age difference. Because of their childhood friend, Miu, the sisters are involved in strange events every day. The sisters and Jasmine Sakuragi suffer in silence, even in the face of Miu's antics. One day, Chika's school is visited by a blonde, blue-eyed beauty, Anna ......

Reference: Baidu Encyclopedia - Strawberry Cotton Candy