Sakura is in a very good mood one morning, which can almost always be attributed to Yukito (all other instances are likely food-related). Sure enough, he’ll be spending the night at her house as he and Touya plan for the athletic festival (sure…why not?).
Despite whispering this to Tomoyo, Syaoran overhears, and then Meiling inserts herself in the conversation. Then Sakura’s mood is totally destroyed by talk of a creepy singing voice coming from the music room late at night—possibly the voice of a g-g-g-ghost!
Even though it’s more likely to be a Clow Card singing in there, the mere fact people are talking about the possibility it’s a ghost sparks Sakura’s crippling phasmophobia, such that she outright refuses to go to school late at night, bowling Kero-chan over.
The thing is, she doesn’t want to leave home anyway because Yukito will be there. But no sooner do he and Touya arrive that he mentions the rumor about the singing voice, and notes how it’s apparently a beautiful voice that he’d love to hear if he could.
Yukito’s request is all Sakura needs to steel herself sufficiently to sneak into school at 10PM with a voice recorder. Tomoyo meets her there and she changes into a pink music-themed battle costume. That said, she’s still extremely on edge, such that when Syaoran and Meiling suddenly appear, she lets out her loudest HOEEEEE yet.
Before long they can hear the voice, and the nearer they get to the music room, the more scared Sakura is, such that she’s constantly asking Tomoyo to assure her it isn’t really a ghost. The strange thing is, the voice sounds a lot like Tomoyo’s. Kero-chan explains that it must be the Song card, which records and mimics the best singing voice it can find.
I knew I was going to run into a number of CCS “firsts” since this is the original series and all, and this episode is no different, marking the first time Tomoyo contributes directly to the sealing of a card. She does so by singing what is admittedly a very pretty song, and Song can’t resist joining her in a duet. Much later, Tomoyo will sing a duet with Akiho while Syaoran accompanies on the piano, leading to the capture of the Record card.
Once the song is over, Song becomes visible, enabling her to seal it. Only her other main objective of the night—recording the voice for Yukito—wasn’t achieved, since she was busy capturing and Tomoyo was busy singing. No biggie; Tomoyo simply needs to sing the song once more, and Song will join her, enabling Sakura to record it and gain some additional EXP.