Tobira wo Akete (1995)

In both of these short anime, a girl is taken through a journey inside colourful and abstract fantasy world. They have a similar feel to them, so if you like one, you will most likely enjoy the other as well. 

Tobira o Akete and Paprika tell us about dreams and the relationship between the dream and real world. A woman and a little girl travel through a delightful variegated reality. Although in Paprika this journey is more dangerous, it's as unpredictable and incredible as the journey of the little girl. 

Both are about a girl who meets a "fairy" that wants to show her new world. While Hanayamata is more slice of life, Tobira wo Akete is more dementia. 

In both there is a surreal and wonderful trip with an incredible animation. I really recommend to watch both, they're fantastic in execution. 

Both are about a girl who is shown a fantasy world by some strange creature. Both have short episode duration.  

similar character design - same director - theme revolves around kids 

A short length and plot deficiency aren't the only things that put Tobira o Akete and Jumping together. Jumping into an urban landscape and flying through a variegated dream world gives you the exact same feelings, and definitely brings the two anime together. 

Random yet interesting surreal events which seem completely out of this world. Extremely short sequences.