D4DJ is a bit of an enigma in terms of what exactly it is. It's not strictly a DJ group, since all they do is just mix and transition music. It's not a band either, since not all of their members play instruments. Nor are they an idol group since their songs aren't pre-made and rather mixed live. It's sorta a bit of everything, an Idol Group that mixes and performs its songs live on stage, and by doing so it seamlessly blends all 3 genres and aspects of music into one seamless transition. It's very refreshing to experience and definitely innovative, and when backed with the right characters and progression of events, the entire anime feels alive and vibrant.
Story
The story of D4DJ is honestly the weakest part about it, and yet even if you're seeing the classic niche events that every Idol/Band anime includes, it doesn't feel as niche as the others. The story follows your classic hotheaded girl who's charisma attracts together a group of people as they attempt to win a title in the local esteemed competition. Along the way the group bonds with a sleepover, some minor conflict happens with at least one member of the group, a study session is held because the spunky ones are always in danger of failing finals, and they persevere with the power of friendship. It's the bread and butter formula of all of these idol groups and this formula has been done to no end. While D4DJ is prone this repetitive formula, the redeeming aspect is not in the main group Happy Around, but rather in its rival groups Peaky P-key and Photon Maiden. The best example I can come up with is sorta like A-Rise in Love Live, a well-established group that serves as formidable rivals to the main group µ's. In D4DJ the extremely well-established and popular group exists in Peaky, but D4DJ also has a ground-up rival in Photon Maiden. This creates a more rough interaction between the groups that leads to them creating a seamless bond that can clearly be seen throughout the anime, one that Love Live's A-Rise failed to create.
Art
D4DJ is one of the few animes to feature CG 3D characters. While they're not the only ones (Argonavis from BanG Dream also uses it), they went way past 11 on it. While their character are basically 3D models, D4DJ still incorporates a lot of cartoony aspects that you normally wouldn't expect. Rinku's reactions are always comically hilarious because they would go nuts with the effects, replacing her eyes with the classic ">.<" face or maybe replacing her eyes with straight up fire emojis when she's fired up. It creates a wonderful comical aspect that you wouldn't otherwise find in animes, especially not animes with 3D CG.
Music
As a music anime, D4DJ's heaviest selling point is in its music, naturally, each group and episode features unique tracks that illustrate the DJ style. The OP itself familiarizes viewers to the concept of DJs, as its comprised of 3 entirely different songs seamlessly blended together in a true DJ fashion. Each group also has its own unique style. Photon Maiden's songs give off a galactic vibe while adhering to their "cool and stylish" mentality. Peaky P-key's songs are powerful and the mixes feel well-made. Happy Around's songs are vibrant and give off a scattered feeling. Apart from that, you can physically hear the aspects each group is gunning for and use the music alone to pre-determine the winner before it is even announced. In the versus round between Photon and Happy, you can tell which song had the most impact on the audience, and in the final showdown the minute you hear the songs it becomes clear what will happen.
Characters
Last but not least, every one of these DJ units has to be supported by a powerful team. The story follows our main 4: Rinku, Maho, Muni, and Rei. The 4 of them create a very distinct and contrasting dynamic that not gonna lie, kinda reminds me of Doki Doki Literature Club. Rinku is the spunky and clearly overcaffeinated main vocalist, Rei is the bookish, quiet, yet talented composer; Muni is your Nico-style cutesy yet kinda egotistic Video Jockey/Arts person, and Maho is the rising star and respectable DJ. Their tropes have been done to no end, yet what sets these groups apart is the dynamic the anime gave to them. Rinku has an explanation for being overhyped because she literally is a monke brain, Maho actually puts herself to her limits to better herself instead of just sitting in front of a desk ruminating about some obscure strategy, Rei's rich upbringing makes her a bit distant but she wants to get to know the group better by actively taking the initiative and even leading some events, and Muni's childhood connection, as well as background support, prevent her from being a Nico Nico Nii joke. The other groups receive just as much attention as well. The dynamic established between these groups makes it so that all their characters, no matter how flat or how much of a cardboard cutout they are, appear in some degree to be rounded and well-developed. Photon Maiden is your classic Cars 3 designer-made tactically optimized group with songs that fit their dynamic selected by a professional record label, but their DJ, Saki, struggles with remixing and wants to create a track that has "its own color". (The way they built Saki as a character makes me think she has Synthesia which is why she's so obsessive about the colors and that just makes that entire episode feel way better). Peaky is the frontrunner of the school, but the character dynamic that many members of its team shares with the main cast in Happy Around makes them feel not like cocky assholes but rather upperclassmen who want to introduce this group of clearly passionate girls the real life of living as a DJ group.
Overall, I enjoyed D4DJ far more than I did any other music-related anime. Their characters shone so much brighter, their dynamics were so much better, and they felt like genuine characters that build their music from the ground up instead of characters built around songs.
