Kurumi and Manami are in the kitchen making chocolates. (In Japan the custom on Valentine's day is for girls to give chocolate to the fellows they care for.) Kyousuke is sitting on the couch drinking some hot chocolate. His dad comes in pursuing Kazuya who escapes into the kitchen where he overturns everything and comes out eating a chocolate bar. He eyes Kyousuke and gets an idea, slamming their heads together to do a mind exchange. Now in Kyousuke's body, he tells him his tooth decay is the result of his not brushing his teeth after eating so many sweets. He'd better get it pulled before he gets a fever. Kyousuke's dad comes in and begins to drag ``Kazuya'' off to the dentist. Kyousuke protests that he's not Kazuya, but that doesn't help. To make matters worse, he remembers his promise to Madoka.
Yuusaku is helping Hikaru make a huge chocolate heart. He thinks that it's great that she's making Valentine's chocolate with the man she's going to give it to. He imagines the two of them alone in an igloo where she gives him chocolate to show her love. She wakes him up from his daydream to stop him from cuddling the chocolate heart. He reads that it says ``I love my Darling,'' and his happy igloo collapses under the rejection.
Kazuya, in Kyousuke's body, is hanging around the park with a bunch of little girls trying to talk them into giving him some chocolate. Komatsu and Hatta come by and kid him about being the only one who would go that far to get chocolate. They then drag him off to school where they can get some.
Master comes into Abcb and comments that Madoka is there early. He notices the tray of chocolates she is making and tries to take one, but she stops him. ``Maybe it's that way,'' he thinks out loud, ``A girl like you would give chocolate only to the man she cared most about.'' She denies that, embarrassed. He also notices a menu she has altered to offer hot chocolate for free. He understands, realizing that Kyousuke is supposed to come by to help. ``None of your business,'' she tells him. He laughs, enjoying the situation.
After Kyousuke, as Kazuya, has been tortured in the dentist's chair, his dad starts talking with the dentist. It turns out she's an old friend of his, and doesn't mind doing this on her day off. She gives him some chocolate for old times sake, and he compliments her on her appearance. Kyousuke excuses himself and teleports away to find out what mischief his cousin is doing in his body. He appears next to Jingoro to ask him, but falls off the roof where the cat is sitting and is forced to teleport again.
Kazuya, as Kyousuke, is at school with Komatsu and Hatta. They are searching through all the shoe lockers to see who's gotten what. He thinks this is a great idea and way to get chocolate and grabs some. The two counter that this isn't meant to be eaten. ``It should be put on an altar and prayed to so we get some next year.''
Kyousuke is wandering around downtown trying to find his cousin and get his body back. He passes a bunch of girls gathered around a ``Valentine Chocolate'' sale run by Ushiko and Umao who are both wearing swimsuits.
Hikaru and Yuusaku meet Kyousuke (really Kazuya) and his compatriots on their way back from school. She runs up and jumps into his arms as usual, but he fails to catch her and she lands on the ground. Her shocked expression is classic. When she sees the chocolate on his face, she grabs him and demands to know where he got it. The stolen chocolate falling out of his coat is too much for her. She takes the chocolate she had made for him, smashes it on the ground, bursts into tears and runs off.
Yuusaku, mad that Hikaru's hurt, flexes his muscles, bursts his shirt like the Incredible Hulk and smashes a paving tile with his head. Komatsu and Hatta have prudently left the scene by now. Yuusaku grabs Kyousuke by the red scarf Madoka gave him, and begins to strangle him with it. ``This is for all the chocolate Hikaru made for you!''
Near the end of the day, Madoka is sitting, dejected, in Abcb. She's written Kyousuke's name on a pad, but crosses it out, mad that he's stood her up. She gives up and begins stacking the dirty dishes for washing. Kyousuke can't find his cousin and his body, but feels he still has to keep his promise, so he goes to Abcb. Madoka welcomes him and gives him one of the chocolates she made. He's hesitant to take it, and further embarrassed when Master tells him he's lucky, ``That chocolate is hard to get.'' He then realizes that Madoka wanted his help to make these. Madoka asks him if he knows where Kyousuke is. He doesn't know but makes a guess he's with Hikaru, which doesn't please Madoka. Just then, Hikaru runs in, crying about Darling, and jumps into Madoka's arms. Unfortunately, Madoka was standing in front of all the stacked dirty dishes and Hikaru knocks her into them, making a big mess.
The three have gone to Madoka's house to clean up. Hikaru is ironing Kazuya's shirt. He realizes he doesn't have the same restrictions as a kid, and steps into the bathroom where Madoka's taking a shower. She suggests that he take a shower with her and drags him in, wondering why he's embarrassed. Hikaru wakes him up from this daydream as she comes by with his shirt. He was only standing in the hall.
Since his shirt is done, his pants are next. She takes off his pants so she can clean them, and she sees what he has under them (same as all men). She is surprised by seeing this and runs around the hall bubbling, ``Oh, hmmm, Oooh! waah!'' This is the first time she has ever seen that! Madoka comes out to see what's wrong. Hikaru continues to bubble, but Madoka tells her to stop embarrassing Kazuya and goes back into the bathroom. Kyousuke, of course, is embarrassed by this whole episode.
Afterwards, Kazuya (really Kyousuke) is sitting on the couch between the two girls. They are wondering why Kyousuke acted the way he did to Hikaru. Madoka surprises Hikaru by saying that he also broke a promise with her today. Kyousuke tries to defend himself (or his cousin), but the girls aren't in a forgiving mood.
Kazuya, as Kyousuke, finally arrives at Madoka's. Thanks to a telepathic warning, Kyousuke beats the gals to the door. He's ready to take his cousin to task, but his toothache stops him. Madoka comes up and asks if ``Kyousuke'' has something to say, and he tries to blame it all on Hikaru. She's not going to forgive him, especially about the ill-used scarf, and grabs him, ready to inflict punishment. Hikaru is surprised that the scarf is Madoka's. She asks to take care of him, picks him up, spins him, and tosses him into Kazuya. The fellows switch back into their own bodies and Kazuya's bad tooth falls out.
Later on, Kyousuke is at Abcb cleaning up the mess. ``He wants to pay for all he did,'' says Madoka, and suggests that Master go home, ``Your wife should be waiting for you, with chocolate.'' He heads out, and Kyousuke sits at the counter, dejected, thinking, ``So I didn't get any chocolate after all this year...''
Madoka puts a cup of hot chocolate in front of him. ``Please don't misunderstand me. I'm giving you this because it was left over.'' Just then, Master comes back in, apologizing because he forgot his hat and adding, ``What a nice smell. Weren't we supposed to serve hot chocolate today?'' Madoka blushes, embarrassed that her lie to Kyousuke has been exposed. She tells Master to go home, and he leaves. Madoka dries a glass, ignoring Kyousuke. He takes the hot chocolate, thinking, ``Then, this is really what Ayukawa was feeling.'' Kyousuke looks up at her, smiles and takes a sip. Madoka smiles back, having forgiven him once again.