Ocean, and Vacations

Ocean, and Vacations (海、そしてバカンス) is the tenth episode of the In Another World With My Smartphone anime.

Plot
Everyone takes in the sight of the beach. Yumina, Linze, Elze, and Yae have fun in the shallow water. Linze wishes they had brought swimsuits, shocking Touya that those exist. The girls ask Touya to take them back to Belfast Mansion, so they can shop in the city for swimsuits. Leen tells Touya 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 into, along with some pool toys and lounge chairs with umbrellas to accommodate everyone. As the girls change, Yumina and Elze stare anxiously at Linze, Yae, and Cecile's 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 greet 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 flusteredly 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 play in the water while Linze sunbathes as she isn't fond of swimming.

Touya is next greeted by Sue and Renne in their swimsuits, telling them they look cute. Renne wants to take some sand home, but Touya offers to take a picture to commemorate the memory. The two then go into the water to play. Cecile surprises Touya, offhandedly complaining her suit is too small (for her breasts); she runs off to keep an eye on Sue and Renne. Touya, watching Cecile'a chest bounce, mutters to himself if the rumor about them floating at large sizes is true. Lapis surprises him next, having heard his vague musings; Touya passes it off as concern over the water doughnuts he made for the kids as he watches Sue, Renne, Cecile, Elze, and Yae play in the water, which Lapis accepts. Lapis explains she and Cecile are on a rotating shift to serve Yumina and Sue'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 as she lovingly hugs him. 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 a swimsuit.

Touya swims to the ruins but cannot go in due to limited air supply. 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).

Yumina and Yae are playing volleyball at the beach 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 contract with him officially; he names them Kokuyou and Sango, respectively. They take chibi form like Kohaku to make it easy to aid him. They return to the beach, where Touya explains he will spend 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 Sue for her cuteness. Linze, Elze, and Yae take it the wrong way; worse, his smartphone falls out of his pocket and shows his photo of Sue and Renne. While the girls now think he's a loli pervert, Yumina can see it's 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 breathe and move like he was on land so long as they were with him. In 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 sky view. A green-haired girl in a blue shirt approaches. Touya turns away, asking her why she is only in her panties.

Characters

 * Touya Mochizuki
 * Linze Silhoueska
 * Elze Silhoueska
 * Yae Kokonoe
 * Yumina Ernea Belfast
 * Kohaku
 * Paula
 * Leen
 * Sushie Ernea Ortlinde
 * Cecile
 * Tsubaki (Mentioned)
 * Kokuyou and Sango
 * Francesca

Spells Used

 * Gate Spell
 * Slip Spell

Notable Places

 * Sky Garden of Babylon

Media Counterpart
Footnote: &dagger; - Partially Nonexistent - 50% or more storyline is missing.

Differences

 * In the LN, Touya invites Charlotte, who turns him down once she learns Leen is coming, but in the anime, she comes anyway.
 * In the LN, when Touya swims down to find the ruins, he can enter the ruins before running low on air, while in the anime, Touya can spot the ruins but cannot 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.

Trivia

 * Despite Micah and Aer joining the group at the beach, they are nowhere to be seen.
 * It is possible that they were playing offscreen.