Additionally, these songs could feature VOCALOID Otomachi Una as a soloist, in a duet, or as part of a group collaboration. For individual song articles, click here.
- "A Halloween Dance With You" by Shikaku dot ft. Otomachi Una
- "Colorful Emotions" by Shikaku dot ft. Otomachi Una
- "Docomo Shop" by deroring ft. Otomachi Una
- "Notice Me" by Syuu ft. Otomachi Una
- "Princess Trish and the Pumpkin Monster" by Parune-P ft. Otomachi Una
- "Two of a Kind" by GHOST ft. Otomachi Una
- "This Special Tone is Wonderful" by Kinoshita ft. Otomachi Una