After Nanami Momozono shares a meaningful kiss with her familiar, Tomoe, she feels on top of the world - until he receives a mysterious black box and declares that he no longer requires her. Inquisitive by nature, Nanami is determined to figure out the box's secrets and concocts a perfect diversion to do so. In Kamisama, Onsen ni Iku, Nanami catches wind of Mizuki, her other familiar, implying that she relies too heavily on Tomoe. This fuels her with newfound drive as she endeavors to prove that she can be self-sufficient. Tomoe takes her to a hot spring resort where they learn about a stone that can supposedly enhance the happiness of couples who touch it together for a lifetime. However, Nanami's pride impedes her from accepting Tomoe's assistance in reaching the stone.