Bakumatsu Rock: Mystery! Onsen Kaijiken ze yo!!

Following a seemingly casual outing to Teradaya, an unforeseen tragedy occurs, leaving a lingering sense of unease within the group. The aftermath unveils a cryptic clue – a numerical marking, "69," branded onto the victim's leg. This unusual detail becomes the central thread in unraveling the circumstances surrounding the death.

The narrative explores the investigation as the characters grapple with suspicion and hidden connections tied to the incident. It’s a story focused on deduction and interpersonal dynamics, revealing the complexities within a familiar social circle. The anime presents a grounded atmosphere, prioritizing psychological tension over action-oriented sequences, prompting viewers to piece together the truth alongside the protagonist. Expect subtle character development and an exploration of how past events shape present realities.