Vacation on the Southern Island

Vacation on the Southern Island is the first Original Video Animation (OVA) in the Resort Boin anime series, released on December 25th, 2007.

The story in this episode focuses on Daisuke's arrival to his grandmother's beach resort, where he's gonna spend his vacations at, and his encounters with Nao and Mitsugu.

Story
The episode starts with Daisuke arriving to the island, admiring the view and all the busty girls in bikini, exclaiming it's going to be an unforgettable summer. Once at the resort's lobby, while thinking about having fun "in his own way", Nao and Mitsugu walk into him and then both of them start arguing over whose destiny was to find him at the island's resort. At the beach's restaurant, Daisuke encounters with his younger cousin Mayaka and her very clumsy friend Momona, shortly after that Nao and Mitsugu arrive and start questioning him about who Maya was; after Daisuke tells them she's his cousin, both Nao and Maya recognize each other and Nao greets her enthusiastically. After Maya runs to Momo after she slipped and fell down while carrying a tower of plates, Daisuke wonders if all of this is his grandmother's doing. Later at night, Daisuke was in his hotel room relaxing drinking a beer after having taken a shower, when suddenly Nao appears at his room's balcony, having used a rope to climb up to Daisuke's window. After a brief exchange of words, Nao takes off her blouse revealing her breasts to Daisuke, who after seeing them gives in and has sex with her, ignoring Mitsugu knocking at his room's door looking for Nao, which annoys her and makes her leave to look for Nao elsewhere. However, she ultimately catches both of them having sex right in the moment where Daisuke was climaxing, freaking him out a little and making him pull out of Nao while still ejaculating. The following night, Mitsugu takes Daisuke to a party on a boat, purposely leaving Nao behind as Mitsugu still resents her for having had sex with Daisuke behind her back. After saying that it was now her turn, she takes off the top part of her night dress and reveals her breasts to Daisuke, and much like what happened with Nao, Daisuke gives in and proceeds to have sex with her right there on deck. The following day, Daisuke, Nao and Mitsugu, along with Maya and Momo, are taking a walk around the resort's greenhouse, with Nao and Mitsugu clinging on to to Daisuke side by side. While chasing after Nao who went running to a banana tree to fetch, Momo trips and falls down, only to be grabbed by a giant carnivore plant that rapes her with its tentacles until she passes out. Once she wakes up, it turns out that everything was just a dream as she had passed out after she fell down to ground after tripping.

Later that night, Daisuke is relaxing at an outdoors hot springs, when suddenly Nao and Mitsugu walk in, he sees them and asks them what were they doing there, and then they inform him that it was a mixed bath. Daisuke later gets a little frustrated for not having realized that before, claiming that if he had, he would've waited for big breasted girls to walk in, to which Nao responds that if what he wanted were big breasted girls, they were already there. After Daisuke achieves an erection rapidly, Nao and Mitsugu proceed to seduce him and the three of them engage in a frantic sex session, in which Daisuke climaxes three times. The following day, Daisuke is hidden behind some rocks while spying on the girls in bikini at the beach with a pair of binoculars, when he suddenly spots Nao hanging out with a blonde man. He overhears them talk, and when the blonde man asks Nao out, she rejects him over Daisuke and explains to him that Daisuke and her do have something, only that Daisuke is too shy to admit it, something Daisuke reluctantly accepts. However the blonde man doesn't take the rejection kindly and grabs Nao's swimsuit and tears the top part off and tries to force himself on her, saying that he wasn't going to let those big breasts to go to another man. Nao gets scared and cries out for Daisuke, who comes across and kicks the guy in the face knocking him unconscious. After saving Nao from being potentially raped, he makes sure she's okay. Feeling extremely thankful, Nao confesses her true feelings to Daisuke, which he also does, then both of them have sex on the shore. At the end, Daisuke and Nao claim their love for each other, and the episode ends implying that they were now officially together.