一心不乱 (Isshinfuran)

Background
The song introduces Umetora's VOCALOID group known as "Divine Diva", which later became a staple of his subsequent works such as 威風堂々 (Ifuudoudou), though at the time IA and Kagamine Rin had yet to be added to the roster.

It was performed live at Nico Nico Cho Party 2013, albeit with Rin performing in place of GUMI.