Hot Spring (オンセン Onsen) is the 13th episode of the Amagami SS+ Plus anime series.
Miya heads to the newly opened hot springs resort with Ai and Sae while still angry at her brother Junichi for not finding her sexy. However, they aren't the only ones coming as the rest of the girls are visiting as well. Hibiki and Haruka arrives to the Hot Springs with Jessica to take a break from their exams with the latter two having fun much to Hibiki's chagrin. Kaoru and Tsukasa bathe in the mineral baths, hoping to make their breasts bigger while avoiding the other well-endowed girls, only to suffer from dizziness from spending too long in the baths. Keiko and Risa become friends over their one-sided crushes. Manaka, Ruriko, Kanae and Rihoko are there as well where Kanae and Rihoko try the footbaths, but Rihoko laughs too much after bathing in the footbaths to lose weight. While Miya has fun groping Sae's breasts, Ai heads to the special bath call "Ramen bath", which leaves her smelling like food. Miss Takahashi goes to sauna, hoping to look younger while avoiding Miya's suspicions. After having a good time at the resort, Miya brings a packet of bath salts for Junichi. Unfortunately for Miya, the bath salts were "Abstinence salts" which, after Junichi uses to take a bath, causes him to have epiphany and reject his old perverted self by burning his and Masayoshi's porn collection, much to Miya's horror.