An AI named Shion Ashimori enrolls at Keibu High School as a transfer student under orders to pass for an ordinary teenager, and immediately sets herself a second goal: cheering up Satomi Amano, a classmate the rest of the school has frozen out. Shion goes about it in unconventional ways, bursting into song among them, and as Satomi's circle, childhood friend Touma Suzaki included, starts to notice, keeping the secret of what Shion actually is gets harder. This manga expands the story of the film Sing a Bit of Harmony.