Asked if she remembers the song she'd heard somewhere, the dying Irina Clockworker is approached by Seth Twiright with a stuffed red cat. As the burned scientist says today is her "Re_birthday," he touches her and Irina spots a light in the sky, remembering the song she'd once heard. She describes how an experiment begins on the night of the full moon as she muses how this "song" changes each era, repeating the "lu li la" melody.
Now in her red cat body some time later, Irina mentions two things becoming one and wonders what her reason for living is. She notes how, once "they" left, they said to continue the experiment alone. Seeing seven lights in the sky, Irina realizes she's living to get revenge on the woman who stole everything from her. Beginning her vengeance under the new moon, Irina then announces she will turn people "evil" as well. She finally describes how the song she heard somewhere, the Clockwork Lullaby, will likely change into a new song eventually.
"Dokoka de kiita koto no aru kono uta Kimi wa oboeteru kai?"
Shinikake no watashi ni chikadzuite
Sou toikakeru kagakusha no otoko
Kakaeteru akai neko no shigai
Watashi no mae ni hourinageta
Yoku mireba sore wa
Nuno to tetsu de tsukurareta nuigurumi
"Korekara kimi wa umarekawaru kyou ga kimi no Re_birthday da"
Yakedo darake no ude de kare ga fureta
"Watashi datta mono"
Kurayami no sora kara sashikomu hikari
Sore wo mite watashi wa omoidasu
Sou kore wa katsute konna uta datta
Mangetsu no yoru ni hajimaru jikken
Jidai ga kawareba uta mo mata kawaru
Watashi no kokoro wa kawaranai
Karada wa akai neko ni natta
Shinu koto wa mou nakunatta kedo
Mou ningen ni modoru koto mo nai
Futatsu wo awasete hitotsu ni kaeta toshite
Ni bai ni wa nare nai
Watashi wa korekara nani no tame ikireba ii no darou
Inakunaru mae ni kare wa itta
"Mou koko ni wa modoranai kimi wa kimi no jikken wo tsudzuke nasai"
Minamizora maichiru nanatsu no hikari
Sore wo mite watashi wa omoidasu
Sou subete wo ubatta ano onna ni houfuku wo!
Mikadzuki no yoru ni hajimaru fukushuu
Karada ga kawareba mokuteki mo kawaru
Ano hito ga watashi wo tsukutta you ni
Kondo wa watashi ga hito wo "aku" ni kaeru
Dokoka de kiita koto no aru kono uta
Izure wa mata chigau uta ni naru darou
Zenmaijikake no komoriuta
“This song that you have heard somewhere, do you remember it?”
Approaching me as I was dying
Was a male scientist who asked me that
He tossed in front of me the remains of a red cat
That he was carrying in his arms
It was a plushie made of cloth and iron
“After this you will be reborn, today is your Re_Birthday”
With arms covered in burns, he touched
‘What used to be me’
A light shines into the dark sky
Looking at it, I remember
Yes, this was formerly such a song
On the night of the full moon the experiment begins
If the era changes, then the song will change again too
My heart hasn’t changed
My body became a red cat
I wouldn’t be dying anymore, but
I won’t be returning to human anymore either
Supposing I joined together two so that they became one
They couldn’t become double
What should I live for from now on?
Before disappearing, he said
“I won’t return here again, continue with your experiments”
Seven lights scatter about in the southern sky
Looking at them, I remember
Yes, I’ll live for retribution against the woman who stole everything!
On the night of a new moon my revenge begins
If my body changes, my goal will change too
Just like that person made me
This time I’ll turn people “evil”
This song that I have heard somewhere
Eventually it’ll become a different song again won’t it?
Full Moon Laboratory shares much of the same melody and lyrics with The Song I Heard Somewhere, Irina making several callbacks to the experiments performed under the full moon and singing in a similar fashion to the mysterious girl of the song.