Nagasumi and his family are meeting with San's mother, Ren. The furious sounds of Gouzaburou can be heard in the next room where he is encased into cement and surrounded by a cage and chains.
The next morning, Nagasumi's grandmother is filled in on the details. She suggests that he take San to the local festival and gives him the money he should need.
Later that night, Nagasumi finds San already at the festival entrance dressed in a lovely yukata. They go to get cotton candy and he tries to pay, but she insists on paying for herself. She gets a gigantic cotton candy. He gets a speck on a stick. He tries to complain, but the owner is an intimidating thug and he declines to push the issue. The same pattern is repeated at the candy apple vendor. Once again at the chocolate banana vendor. This is slightly different because Nagasumi almost puts the barrel of a chocolate covered pistol in his mouth. Has he looks around it seems that all the vendors are after him. Nakajima Octopus is even at the roasted octopus stand. San tells him that all the vendors are supported by her family.
They walk past the mask vendor and Gousaburou is watching them walk past. Nagasumi wants to hold her hand, but feels like if he did he'd be killed. This is when she asks to hold his arm.
They pass by the takoyaki vendor and he gives them both rather large servings. Nagasumi is touched until he breaks his open to find a cell phone inside. It rings and he answers. It's Gouzaburou on the line threatening his life. He tries to act like nothing has happened so he doesn't ruin San's mood.
San sees a child pass by with goldfish and decides to try that. Not to keep them as pets, but she sees it as rescuing them. Nagasumi tries to join in, but he is directed to another station is is filled by Shark Fujishiro. San notices him, and Nagasumi is able to save himself with surprising skill driven out of a will to live and he tosses Shark Fujishiro.
The splash of water Shark caused hit San and her mermaid tail is showing. Nagasumi removes his shirt to cover her tail and carries her off. If he dries her feet they will return to human form.
Later at the festival, Ren is walking with Gouzaburou. She wonders how the kids' date is going. Gouzaburou silently communicates with Masa about the plan to trap and kill Nagasumi. Ren is suspicious of her husband's behavior. All of them suddenly notice the sound of Nagasumi and San. From the words and what they can see, it appears that Nagasumi is sexually 'groping' San between her legs. Ren seems happy about it, but Gouzaburou snaps and tries to kill Nagasumi.
Only now is the truth revealed as San's legs return to normal. He wasn't doing anything inappropriate he was just trying to dry her legs. This prompts Masa to try and stop Gouzaburou since it's just a misunderstanding. It also appears Nagasumi's mother and father were nearby as well. Ren is actually disappionted to learn that Nagasumi wasn't trying to sexually molest San, and tells him he has to improve.
San points out that she's aware of what her father has been doing and is angry with him. She demands he apologize to Nagasumi. Through pressure of his daughter he doesn't apologize, but tells him he will let him off this time and leaves.
Masa asks San to return home, but she refuses. She takes Nagasumi and runs back to the festival. Ren offers Masa some roasted octopus, but he asks if that's part of Nakajima Octopus. She's not sure and still starts eating.
Back at the festival Nagasumi asks about how mermaids still mingle with humans. She tells him that she goes to a local human middle school. The principle is a mermaid so there isn't as much to worry about. San trips over a bucket of water and her tail is exposed. A little later they are laughing. It seems San is naturally clumsy. She even suddenly falls into another water themed stand with her tail exposed.
Before the dance begins they announce they will be spraying the grounds with water to prevent the ground from loosening. Shes relaxed despite standing right in front of a water bomb stand. Nagasumi tackles her to save her from being splashes by a thrown bucket of water. Inadvertently, his hand slipped into her top and onto her breast. She panics and suddenly she strikes him with a sonic scream that is like an explosion. She apologizes for attacking him so suddenly, but his ear drums are damaged and can't hear anything. Mermaids have the ability to use their voices as weapons.
Nagasumi wants to cheer her up and offers to by her some blow glass art. She selects a glass ring and wears it on her ring finger.
The dance begins. San dances while Nagasumi watches. Masa appears to teach him to to the dance. San sees this and thinks Nagasumi would rather be with Masa then her and she runs away heartbroken. Nagasumi chases after her.
He catches up to her, but her ring is missing. Nagasumi doesn't seem bothered since it was just a glass ring. She asks if their marriage is like that to him as well. That it's made of glass and doesn't have much meaning. To her the ring is a symbol of the marriage and those things mean the most to her. Moved by her words and tears he starts to look for the ring as well. Gouzaburou is nearby and hears the conversation.
After sine searching, Ren and Gouzaburou walk up. Seems that he found the ring they were looking for. Ren tells her that when she last wore the yukata that San is now wearing is when Gouzaburou proposed to her with a ring. He becomes so embarrassed to throws the glass ring away. It travels not too far away and lands on the ring finger of Masa. San is so shocked she lets out another ultra-sonic mermaid scream that catches Nagasumi in it's wake.
Nagasumi's spirit is floating through heaven and finds his grandfather. His grandfather tries to convince him to stay with him the the sound of San's voice revives him. He's revived and San clings to him crying and apologizing. This time his whole body is injured.
The next morning, Nagasumi is in a full body cast and tries to play that he's fine while San is at his bedside. She wearing the ring on her ring finger.
Ending Theme: "Asu e no Hikari"(明日への光) by Asuka Hinoi; written, composed, and arranged by Yugo Sasakura.