Everyone takes in the sight of the beach. Yumina, Linze, Elze and Yae have some fun in the shallow water. Linze wishes they brought swimsuits, shocking Touya that those exist in this world. The girls ask Touya to take them back to Belfast Mansion, so they can go shopping in the city for swimsuits. Leen tella Touya that she doesn't mind letting them have fun instead of looking for the ruins. Touya invites Cecile, Lapis, Renne, Lyon, Micah, Aer, and the royal family to join them.
Touya creates tents for people to change in, along with some pool toys and lounge chairs with umbrellas to accommodate everyone. As the girls get changed, Yumina and Elze stare anxiously at Linze, Yae and Cecile'a busts. Leen jokes to Elze that Linze must be the eldest twin, prompting Elze to snap at the fairy.
Outside, Touya is in his own suit; he's looking at the ocean with Kohaku. Elze, Linze and Yae great him; Touya promptly gasps at their beauty. Elze is in a pink striped bikini; Linze wears a matching blue one with a light blue jacket. Yae wears a pure purple bikini. They ask if Touya likes their suits, and he responds in a flustered manner that he finds them cute. Yae adjusts her bikini bottom, saying she's not used to non-Eashen clothing; accidentally exciting Touya's libido. Elze and Yae go play in the water, while Linze sunbathes.
Touya is next greeted by Suu and Renne, telling them they look cute. Renne wants to take some sand home, but Touya offers to take a picture to commemorate the memory. Cecile surprises Touya, offhandedly complaining her suit is too small (for her breasts); she runs off to keep an eye on Suu and Renne. Touya, watching Cecile'a chest bounce, mutters to himself if the rumor is true about them floating at large sizes. Lapis surprises him next, having heard his vague musings; Touya passes it off as concern over the water doughnuts he made for the kids, which Lapis accepts. Lapis explains she and Cecile are on a rotating shift to serve Yumina and Suu's mothers (who are sunbathing with their respective butlers guarding them).
The king and the Duke are having a swimming contest, with Lyon starting to outpace them. Touya is greeted by Yumina, who he also calls cute in her suit. However, he flinches when she tells him she picked out her white bikini with him in mind. Touya turns down her request to play by saying he has to help Leen investigate the ruins. Leen walks up behind him in her swimsuit, tricking him into picturing Tsubaki in swimsuit.
Touya swims to the ruins, but he cannot go in due to his air supply being limited. Leen is disappointed, but Kohaku reveals she knows an entity with dominion over water. This leads to Touya summoning the Black Emperor, an old friend of Kohaku's; a turtle and snake who share the title. To form a contract with the Black Emperor, Touya has to prove himself by defeating them; he casts an infinite Slip Spell to have the turtle trip repeatedly, dizzying both the Black Emperor(s).
At the beach, Yumina and Yae are playing volleyball against Linze and Elze. The Silhouseka sisters win, but Linze's bikini top falls off. Linze covers herself, calling Touya to help; Else frantically tells her not to call him, getting her sister's top back on. The girls sit by the shore later, wondering where Touya is; Yumina mentions he was helping Leen search for the ruins.
Back to Touya. The Black Emperor admits defeat to Touya; having become too dizzy to move. They ask for new names to officially contract with him; he names them Kokuyou and Sango respectively. They take chibi form like Kohaku to make it easily to aid him. They return to the beach, where Touya explains he will be spending time with the girls. However, they are highly suspicious of the time Touya had with Leen. They demand to know who looks best in a swimsuit to him. Unable to choose, Touya picks Suu for her cuteness. Linze, Elze and Yae take it the wrong way; worse, his smartphone falls out of his pocket and shows the photo he took of Suu and Renne. While the girls now think he's a loli pervert, Yumina can see its a misunderstanding with her mystic eyes. She pulls Touya to the water with the other girls joining them.
At sunset, Touya asks Kokuyou and Sango for help; they cast a barrier to repel water, allowing Touya to breath and move like he was on land, so long as they are with him. In the ruins, Touya finds a teleportation relic; his familiars tell him to pour magic into it. The teleportation activates and takes them to a garden with a view of the sky. A green haired girl in a blue shirt approaches. Touya turns away, asking her why she is only in her panties.
- Touya Mochizuki
- Linze Silhoueska
- Elze Silhoueska
- Yae Kokonoe
- Yumina Ernea Belfast
- Kokuyou and Sango
- In the LN, Touya invites Charlotte, who turns him down once she learns Leen was coming, but in the anime, she comes anyway.
- In the LN when Touya swims down to find the ruins he is able to enter the ruins before running low on air, while in the anime Touya is able to spot the ruins but is unable to enter it before running low on air.
- In the LN when Touya summons the Black Emperor all of the girls are present (Elze, Linze, Yae and Leen), while in the anime only Leen was present
- In the episode, Yae says she's not used to restrictive clothing like swimsuits; she lightly tugs on her bikini bottom to adjust it, unintentionally making Touya uncomfortable. In the light novel, she makes no mention of this.
|Anime||Light Novel||Web Novel||Manga|
|Episode 10||Volume 3||Chapter II||Arc 9||Chapter 61||Not Available|
Footnote: † - Partially Nonexistent - 50% or more story line is missing.
- Despite Micah and Aer joining the group at the beach, they are nowhere to be seen.