ハッピーシンセサイザ (Happy Synthesizer)

Background
"Happy Synthesizer" is a bouncy techno-pop love song about wanting to play a melody that will reach your beloved's heart. Considered a staple of VOCALOID music, it is by far EasyPop's most popular song, with over three million views on Niconico. The most popular reprint on YouTube has garnered over nine million views.

This song is featured on the compilation albums EXIT TUNES PRESENTS Vocalonation feat.初音ミク, POP THE HATSUNE MIKU, VOCALOID BEST from ニコニコ動画(あか), VOCALOID Duet Collection, and VOCA NICO☆PARTY. It is also featured on EasyPop's album EasyPop VOCALOID Tracks 2. Covers and remixes are featured on additional albums.

Sheet music
Sheet music for this song was released in the Vocaloid Superselection piano solo collection and in the Vocaloid Super Hits (guitar) collection.