Kaijuu no Kodomo

Both series use a lot of allegories to explore themes like the birth of the universe, singularities and human nature. Also, both of them are a visual delight, using some psychedelic sequences at the final leg of the movie to illustrate their message.  

At first glance, these movies might seem quite different, but the feeling of existential confusion, dread, and delight that they both manage to fill me with is hard to ignore. By the end of each one, you will be left pondering your own humanity and existence. I won't spoil the details, but they deal heavily with what it means to live, to be human, and to exist in the world. The art direction is top notch in both, featuring some of the most interesting and dynamic uses of "camera" movement, framing, and character morphing I've ever seen. They aren't afraid to go off-model a bit if it adds meaning to the scene. Music is also stellar in both. If you want a well directed and delightfully philosophical and psychological journey, you can't go wrong with either of these. read more 

First of all - they both share a similar artstyle, which is very unique to both. Second, both share a very similar atmosphere and has the theme of fanatsy in a world that is pretty much similar ot ours, with a lot of moments that just feel magical. If you liked one, you should definetly watch the other (though I think the Manga of Kiajuu no Kodomo is better, but the adaptation is also amazing). 

Both shows allow the natural world to flourish organically as it intertwines with the plot. Both also have characters who approach the world philosophically and scientifically in their own ways. Finally, both emphasize how little humans (May ever) know about nature, and emphasizes the ways in which people are captivated by its beauty, mystery, interconnectedness, and danger. There’s a sense of magical realism with each and its visually stunning.  

Obviously both deal with the sea, but I would say they also have similar themes of connection to nature/living with nature. They are tonally quite different, one being a romance drama and the other being much more of a spiritual journey, but there are some overlaps in mood. 

Both are takes on the meaning of life and being human, and whether the roles of men and women in this life are different. Both movies do not give straightforward answers and ask the audience to puzzle out the complex symbolism. Whilst Kaijuu no Kodomo is set within a modern human society and goes into more progressive ideas around the roles, and Tenshi no Tamago explores it in a more traditional route within a dystopia, they are both about how humans relate to nature. 

Both involve a lot of aquatic life and oceans and have stellar animation 

The ocean doing some weird, bizarre, and unnatural things in the background while the story primarily focuses on the great adventure towards the discovery of a young girl in the world she lives in. 

Both films are very beautiful films and have relatively traditional setups and become more complicated and confusing as the story progresses. Both take deep influence from traditional Chinese/Japanese religion and mythology. 

Supernatural and Mystery centred beautiful anime movies, which put forward lot of philosophical question about the existence of human being or any other living form.  

Both are sort of coming-of-age films, following a young girl's journey that is filled with fantasy and mystical elements. Both films have great animation and lots of symbolism. 

They each touch on themes of motherhood, and feature a child longing to connect to and explore the natural world  

Coming-of-age as depicted through the lens of highly existential psychedelic escapades. Don't do drugs, kids. 

Both films have this sort of "summer" feeling, as in they're films you'd enjoy on a hot summer day. Also both are films focus on a rather unsociable young girl and her journey of self-discovery, using also fantasy and symbolism to drive the narrative in a "magical realism" kind of way. 

Both films have: - Incredible work with animation and graphics - The presence of philosophy and symbolism - The final, where something brain-breaking happens - Unusual approach to the story. If you are a big fan of Satoshi Kon films, then you will like this movie.