Ever since we were kids, me, Rin, and Kazuma have been best friends. Today, we're on a hot spring trip that Kazuma arranged for the two of us. Laughing about how it felt like a scene from a drama, Kazuma signed as witness on our marriage registration when Rin and I tied the knot. That night, the three of us were drinking and reminiscing in the lounge, but as closing time approached, I headed off to the hot springs ahead of them. When I came back from the bath, I noticed Rin wasn't in the room and started to worry, so I called Kazuma—but...