It's the umi (beach) chapter and it comes so early in story (6 volumes and counting from what I've been able to gather). In chapter 5, Sachie's grandfather gathers the household to go to an inn on the beach that is run by an old friend of his. Sachie worries about the nature of this friendship, suspecting that it has something to do with yakuza. But her fears are put to rest as it seems that Ume is really an old friend.
Sachie is, of course, is looking forward to spending time at the beach, but when they get there she finds it difficult to let loose because she is surrounded by her gruff looking protectors. Finally away from her "family", Sachie quickly gets into a pinch as she defends a beach food vendor from the insults of a very rude and wasteful couple. They claim the vendor's food is of low quality and don't want to pay (I think ...) and end up dropping the food on ground as they leave. Sachie stops them and tells them the food is fine and not to waste it. The couple gets defensive and confronts Sachie and then Raku comes to Sachie's side to protect her. He knocks down the male of the offending couple. Raku scolds Sachie for being reckless and says that if anything were to happen to her it would crush his heart. Sachie, as usual, thinks he's being weird and overly dramatic and walks off muttering to herself.
As she sits on some steps complaining, the young man that was running the food stand comes to thank Sachie for saving him and offers her a beverage while generally trying to flirt with her. And in comes Raku, who is carrying what appears to be a bag with food. He quickly sequesters Sachie, taking her arm by the wrist with one hand and covering her eyes with the other. (To me this looks very possessive as if to imply that he does not want Sachie to touch or ever look at another man. I feel as though I should be offended, but for some reason it seems very old fashioned and sweet in a childish way). He informs Sachie that there is food and beverage back at where they are staying and returns the vendor's drink with one of those fake smiles.
Sachie and Raku return to the inn for dinner and are introduced to Azuma, the innkeeper's grandson, who happens to be the food vendor Sachie saved earlier. Azuma and Raku face off with Sachie inbetween. There are lighting sparks between them and everyone notices it. Azuma tries to introduce himself to Sachie with a handshake, but his hand is intercepted by Raku, and it appears that some knuckle squeezing may be happening. The innkeeper requests that Azuma show them all to their rooms.
Later, Sachie has a watermelon -- her favorite. She puts it in the fridge to chill in anticipation of breaking it open later. Like a child she writes, "Sachie's watermelon" in hiragana on the skin. Then Sachie wonders off and spots Raku dozing. She supposes he must be tired from all the running around he did that day. As she was looks at him, she thinks he seems like a prince as he sleeps. He opens his eyes and tells Sachie to cheer up soon so they can go out and have fun together. He has a "bedroomy" look on his face. Sachie is surprised and Raku wakes up fully and looks as though he doesn't know how "bedroomy" he just seemed.
Azuma is working hard in the inn and Sachie is complaining as Raku follows behind her apologizing and generally acting subservient. Azuma looks upon the scene, cursing that he has to work, and declaring war against Raku. Ume asks Azuma to start preparing the meal and as he does so, he comes across Sachie's watermelon in the fridge. He decides to serve the watermelon thinking that he will score points with Sachie because watermelon is her favorite. And so everybody is enjoying Sachie's watermelon and when Sachie walks in on the scene, she is devastated and passes out. Raku instantly understands that since Sachie had written her name on the melon, she had something special in mind for it that she wanted to take the lead on.
Onto the next page ... Sachie is squatting in the waves lamenting the loss of her watermelon, when Raku shows up with a small round watermelon on which he written "Sachie-sama's" on the skin in Kanji. He approaches her telling Sachie that he has found her lost item -- a small round and easy to carry watermelon. Sachie then recounts getting a watermelon with her Mom. Her Mom teased that the watermelon was too big for just them, but then found a small round that Sachie could eat. Ah, but what about the thick skin. Child Sachie proposes they break the melon, and so goes Sachie's wonderful childhood memory. At first, jokingly, Raku offers Sachie a sword to break the melon, but then blindfolds her and gives her a stick and tells her to go at it. Sachie wanders off to somewhere nowhere near the melon. Raku directs her back towards the watermelon and when she is near it he does the old, teach a women how to hold a bat trick on her. Standing close behind her and holding her hands on the stick he directs her to the final location of the melon and helps her break it. Sachie thinks about how close they are and the possibility of separation. Somehow, magically, they end up in the water, Raku on the ground and Sachie on top. Sachie still blind folded asks if she indeed broke the melon and Raku pulls the blindfold off and tells her she really did.
Sachie then asks why Raku did this for her -- buying the melon and bringing it to her. It's as if they are going out she says. Then she nervously asks if he will let at her be at his side now. (They look as though they are reaching out to hug one another.) To which Raku replies, "This me and no other will be at your side" as he plays with her wet hair.
Meanwhile back at the inn, the "family" wonders what happened to Sachie and why Raku took off in such a hurry to get another watermelon. Azuma realizes that he didn't understand the significance of the watermelon to Sachie and that Igarashi (Raku) is probably spending some quality time with Sachie -- score one for Raku.
Back at the beach, Sachie is surprised by the seriousness of Raku's reply and blushes furiously. Raku suggests that they return and the chapter ends with narrator saying, "this year's summer seems hot."
