Unformed Delta - music

Metadata patterns not accounted for by music apps

Wed, 22 Apr 2026 06:34:00 +0000

I hesitated a lot when first getting into anime idol music. I was definitely a little self-conscious that the album art can get fairly suggestive.

13+ album art with characters wearing swimsuits

But more importantly I feared its complexity would render my music cluttered and unnavigable. I mostly engaged with my music navigationally as opposed to searching. I liked to select a genre, an artist within that genre, and then pick out an album within that genre to listen to. Instead of staring at an empty search field, wanting music for focusing, I could pick Soundtrack, evaluating that Joe Hisaishi (i.e. Ghibli Soundtracks) was chiller than John Williams (Star Wars), then Spirited Away, deciding Princess Mononoke was too gloomy and I needed a little more whimsy.

Idol music would seriously upset this balance. Many tracks were only available as singles, and — GASP — would need to learn to organize my music into playlists. But as listening to nightcore music on YouTube transitioned into watching Love Live! Sunshine’s Aqours’ lyrics videos, eventually I decided that the sanctity of my navigable music library would need to be broken, and started adding μ’s and Aqours music to my music library.

When I got tired of manually importing metadata I discovered beets, a command line tool that automatically tags music with MusicBrainz metadata. This kept my music organized, but once I was listening to a huge number of artists and franchises¹, navigability in my music player started to break down, none the less.

Character vs Voice actor

Each character is portrayed by a voice actor. Voice actors often also publish music as themselves, and sometimes the same voice actor portrays multiple characters². If I want to listen to music by a particular singer because I like their voice, I’d love to be able to jump to all of the music by the voice actor. YouTube Music/Spotify usually doesn’t even show the voice actor (it depends on the franchise).

Deep hierarchies

Because idol anime franchises are primarily a vehicle for selling merchandise for a huge number of characters, they end up with tons of characters sorted into different units (groups of characters that perform together). Idolm@ster is a particularly illustrative franchise³: it contains at least 8 sub-franchises, of which Idolm@ster Shiny Colors contains 8 units, of which Noctchill contains 4 members.

Overlapping hierarchies

Groups aren’t even static a lot of the time. In Idolm@ster Million Live, pretty much every new single features a never-seen-before unit. Fortunately, when credited as artist these units usually include list of their members, which makes it possible to find songs containing a particular character through search.

So fans are confident their favorite character will get a new song eventually, albums/singles are often sorted into series⁴. I often wish I could navigate between albums in the series while listening to music.

Tracks you typically don’t want to listen to

Albums often bundle tracks that don’t make to listen to typically. Most albums include karaoke tracks without vocals, plus there’s often also drama tracks with character story. These are sometimes interesting to listen to, but I don’t typically want my music listening to be interrupted by a podcast.

Beyond that there’s often variants of the same song: solo versions, short versions (i.e. ~1:30 versions used in rhythm games), and live recordings. MusicBrainz’s data model actually works fairly well for variants, linking recordings to a single song, but I haven’t found a music app that allows navigating these relationships.

Music apps aren’t able to filter these out for general listening, but still expose them when desired.

Navigability

None of these matter when listening to an algorithm generated playlist on Spotify or YouTube Music. But regardless, I still have a strong desire to navigate — I think it helps me feel more intentional about my music listening.

Classical music once had a lot of similar problems, e.g. the same piece but separate recordings different orchestras/conductors. Eventually, Apple implemented better navigability through specialized services like Apple Music Classical.

Fan wikis + searching were sufficient to give me the navigability I desired, but perhaps Claude will make it possible for us to create the bespoke navigation patterns we desire.

nayuta, Idolm@ster, Love Live!, Project SEKAI (especially More More Jump! and Nightcord at 25:00) are my favorites. I’ve even gone to a couple of live shows in Japan. ↩
Ruby Kurosawa and Airi Momoi’s voice actor are both Ai Furihata. ↩
https://project-imas.wiki is organizes all this complexity neatly. ↩
For example there are 7 albums in THE IDOLM@STER SHINY COLORS “CANVAS” series (just numbered 01 through 07). ↩

空色♡ Birthday Card

Thu, 09 Apr 2026 02:00:00 +0000

I’m a bit of a data hoarder. Among other things, I never remove birthdays from my calendar once I’ve added them. Sometimes this leads to a pang of heartbreak when I look at my calendar to see it’s the birthday of a past crush. 空色♡ Birthday Card (literally: Sky-blue Birthday Card) captures my experience of this.

I’ll excerpt and translate the relevant lyrics; if you’re interested you can find the complete lyrics and a translation on the Idolm@ster Wiki. If you want to listen, I prefer the short MV version of the song anyways¹, or here’s a link to the full length version on YouTube Music:

大丈夫だ、って　もう平気だ、って

“It’s fine”, “I’m calm now”

The song has a chill, acoustic instrumentation. It reflects a peaceful, calm mood before the surprise of having been reminded of my past crushes’ birthdays.

そうだ… 忘れていた赤い◎(にじゅうまる)

Ah… it’s the red double circle I’d forgotten about

Even years later, just seeing the all-day calendar event can make me briefly drift into thinking about what ifs and counterfactuals.

(ふわ　空に溶ける)
Happy Birthday
(Far　遥かきみへ)
おめでとう

(Softly, melting in the sky)
Happy Birthday
(To you, far away)
I wish you Happy Birthday

These lyrics echo like the ruminative ifs and counterfactuals and my wish to wish them happy birthday.

(願ってるよ)どうか笑顔でいてね
“友達”として

(I wish) for you to keep smiling
As a “friend”

An unrequited crush feels paradoxical. After being rejected, my feelings remain strong and I want little more than to spend time with my crush, but it’s hard to tell whether I’m acting out of my selfish desire or in their best interests. I can only try my best to respect their wishes and act as a friend.

愛しい日々をありがとうね
きみに恋をしてよかった

Thank you for the precious days
I’m glad I loved you

I typically end up taking something away from an unrequited crush, and longer term don’t end up regretting having confessed my feelings. Usually, I end up recognizing that there was something I envied in the other person.

(見上げたら)ちゃんと笑顔でいよう
私らしく

(Looking up at the sky) I’ll try to smile
properly authentically

This helps me understand myself better, and become myself more authentically. I’ve learned to better explain why I like things, to be less ashamed of sharing even the obscure things I like, and to be more aware and present.

いつかいつか　ありがとうを

Some day, I’ll thank you

After drifting apart, it becomes possible to recognize that rather than being genuine, the desire to thank them for the insight I gained was mostly an excuse to have contact with them.

飛行機雲
なんとなく今日は
優しい消印みたい

In the vapor trails
Today, I’m able to make out
a friendly looking postmark

But the desire stubbornly sticks around, everyday occurrences end up being reminders. Over time, resisting, this impulse fades. Reflecting this, the ruminative echoes reprise.

First, just the parenthesized longing reprises without an action to express it.

(Far　空に溶ける)
(ふわ　遥かきみへ)

(Far away, melting into the sky)
(Softly, to you)

Then at the very end of the song the thanks is only written into the sky.

(ふわ　空に溶ける) Happy Birthday
(Far　遥かきみへ) 指先で「ありがとう」

(Softly, melting into the sky) Happy Birthday
(To you, far away) with my fingertip, I write thanks.

After all, the desire to thank them was mostly for catharsis, not for their benefit. If they are no longer in my life, I can be grateful for the impact they had on my life without needing to convey my thanks to them.

I went on what I thought was a “date” just two days before my birthday. Naturally, their birthday ended up on my calendar. I told them I liked them, but my romantic feelings were unreciprocated. I’m aware how I will likely feel when that date comes up on my calendar. And yet, I won’t remove it.

The verses are sung in relay with a rawer, more intimate feel than the full length version where the verses are sung in chorus. ↩