This Anime / Music Video is a short for the iMarine Project, a Co-Brand digital Idol "iMarine-chan" of the character Marine-chan from the show Umimonogatari (https://myanimelist.net/anime/6129/Umi_Monogatari__Anata_ga_Ite_Kureta_Koto). Since this is about an Idol, the focus lies on the music aspect, of course. This 9 minute Anime is the longest "video" in a row of music videos from iMarine-chan and tells a bit of a story about the characters and the world, while containing the ~3 Minute Music Video "Deep Blue Town". I liked it a lot because the characters are very cute, and despite not speaking a single word japanese I understood the rough concept and scopeof everything.
The main reason though why I gave such high scores is the absolute hype and good mood spread by this music. For me this is an absolute banger and I can't sit still listening to it.

The Animations are well made as well, fluent and high quality, and there is a lot of eye candy to behold.

The Soundquality is very high of course, since this is the whole reason this short exists in the first place.

If you liked this short, I would strongly advice looking up the other shorts and listen to them, and maybe even watch Umimonogatari.