DELUTAYA (Δ.DELUTAYA) has released a cover of ハッピーシンセサイザ (Happy Synthesizer), and it’s not just a standalone single — it’s the lead track off her limited-edition first indie Cover EP, Δ.MEMORIES, dropping the same day. For a song this foundational to Vocaloid culture, leading an EP with it is a real statement about where DELUTAYA’s own roots as a singer sit.

One of Vocaloid’s Defining Hits

Happy Synthesizer is about as canonical as Vocaloid songs get. Written and composed by EasyPop (credited here under the name BETTI) and originally released in November 2010 featuring Megurine Luka and GUMI, it crossed a million views on Niconico within a year and has since been featured across nearly every major rhythm game — jubeat, maimai, GROOVE COASTER, Project SEKAI — cementing it as one of the genre’s genuine standards. It even resurfaced as recently as this year, appearing as an insert song in the Netflix anime film 超かぐや姫！(Cosmic Princess Kaguya!).

A Cover With the Original Writer’s Own Involvement

What makes this particular cover notable is that EasyPop himself is credited directly on the lyrics and composition — this isn’t just DELUTAYA singing over someone else’s decade-old backing track, it’s a version with the original creator’s own hand still in it. Arrangement comes from Ryota Teshima (手島涼太), with mixing from T4K.

Part of a Bigger Debut

DELUTAYA debuted as an independent VTuber and utaite in 2022 before joining MeSTAGE — a “music x eSports” VTuber project run jointly by SCARZ and Victor Entertainment — in October 2025. Δ.MEMORIES marks her first physical cover EP since that move, and picking a song this iconic to lead it says she’s not shying away from comparisons to the genre’s biggest names.

The Visual Side

Illustration comes from Karei026, video work from kyo.京, with Tatsuya Doi of LumyneX directing the illustration and MV overall, and production coordination handled jointly by LOVE ANNEX and LumyneX.

Track Credits

• Title: ハッピーシンセサイザ (Happy Synthesizer)
• Vocals: DELUTAYA (Δ.DELUTAYA)
• Original Song By: EasyPop
• Lyrics & Music: BETTI (EasyPop)
• Arrangement: Ryota Teshima (手島涼太)
• Mix: T4K
• Illustration: Karei026
• Video: kyo.京
• Illust/MV Director: Tatsuya Doi (LumyneX)
• Agency: MeSTAGE

▶ Watch: DELUTAYA — ハッピーシンセサイザ (Cover) on YouTube