Bakumatsu Rock: Mystery! Onsen Kaijiken ze yo!!

During a seemingly ordinary day trip to Teradaya, a shocking incident unfolds when a death occurs, casting a shadow over the group's outing. As they grapple with the unexpected tragedy, a cryptic "69" tattooed on the victim's leg emerges as a crucial clue, prompting the gang to delve into the mystery surrounding the event.

Amidst the blend of music and intrigue, the characters must navigate their own emotions while piecing together the circumstances that led to this grim situation. With the clock ticking, they embark on a journey of discovery, where each revelation brings them closer to the truth—and to one another.