Hajime Yasaka goes to stay with his grandfather over the summer in a small town. While he's there, he meets a girl, Sayoko Arashiyama. "Arashi" for short. When the two join hands, Arashi reveals that she "connects" with Hajime, and that she is also a ghost. When they connect, Arashi and Hajime can jump through time, which Arashi uses to show Hajime the past and, with his help, to correct it. In the present, she gets to know the modern era and work with the colorful cast of people at the cafe Hako-bune ("Ark", e.g.Noah's).Based on the manga by Jin Kobayashi, creator of School Rumble, and adapted into an anime in the spring of 2009 by Studio Shaft, with a second season, Natsu no Arashi! Akinaichuu, airing in the fall of that year.
Tropes in Natsu no Arashi! include:
Arbitrary Skepticism: Hajime was incredibly suspicious of Arashi at first, being a science nerd. But an E.T. like moon leap was all it took for him to accept her. Sort of.
Clingy Jealous Girl: Kanako towards Yayoi at times. When it's revealed that Yayoi can connect with the Master as well, she wonders if Yayoi was corrupted by connecting with her.
Cool Big Sis: Master, to a degree, Shades even calls her "nee-san" from time to time. Makes one wonder, how old is she...
Cool Shades: Hideo, the man with the sunglasses hunting for Arashi.
Couch Gag: Another part of a story about a mangaka, his girlfriend, and some aliens is shown in every episode's opening; the colors used for the nude Master and Yayoi, Kanako, Kaja, and Arashi silhouettes is also different every opening.
Cute Ghost Girl: Arashi, Kaja and Yayoi, though they don't display many "ghostly" signs. A slightly less cute one, Kanako, displays some more.
Date Peepers: Time traveling date peepers. It's entirely possible.
For Want of a Nail: Sankichi, a young man that Arashi saves in the past, goes on to become the father of Hideo, the man with the shades tracking her down in the present. See Timey Wimey Ball below for more on how Hajime and the rest dissect this issue.
"Freaky Friday" Flip: Jun and Hajime swap bodies, which Jun finds troublesome. Mostly because of the gender issue.
Gender Vocabulary Slip: Rather rare in public with Jun, but she goes ahead and slips right back into "watashi" when people aren't around. Rather softens the blow of the"reveal".
Glamour Failure: All video with Arashi recorded on screen has noise running through it. Hints, hints.
Here We Go Again: The last episode is a mirror of the first episode in many ways, right down to the titles. Which are, curiously, out of order. "Playback Part 2" was the first episode and "Playback Part 1" is the last.
Medium Blending: A gag that gets used a few times is a cutaway to a shot of the Hako-bune getting wrecked as a live-action model.
Meganekko: Everyone in episode 5 of the second season, when Master announces "Meganekko Day" for all of her workers. Speciffically, to make Kanako wear glasses, which gets her transformed into a Mahou Shoujo, to her great horror.
Mundane Utility: Time travel powers are abused to speed up fermenting time and to make doing things around the Hako-bune easier. Jun wonders if that's such a good idea.
Never the Selves Shall Meet: The rules of time travel work as such: If you meet yourself, you vanish. Time doesn't want there being two of the same person in the same area. Maintaining a safe distance is necessary. This also makes it easy to whether you're, say, hiding around the corner, however; the closer you get to yourself, the more you fade out.
Oddly Named Sequel - The second season is called "Akinai-chuu" meaning "Open for Business". Ignoring the fact that the main characters already spent 12 episodes working for the Hako-bune in the first season.
Actually... "Akinai Chuu" isn't written the way you'd normally write it. In Natsu no Arashi!, the word "akinai" meaning "business" is written with kanji "spring", "summer" and "winter". Missing the "autumn", eh? Japanese for "autumn" is "aki". No autumn = aki nai. Remember? Should the autumn come, Arashi and the crew will disappear, so the title holds special significance in that sense.
Once an Episode: There's almost always the man in the back of the Hako-bune, asking for salt. He even goes so far as to interrupt Hajime's timeline graph to ask. At this point, the cast is probably not aware he exists.
Throw the Dog a Bone: After 26 episodes spread across two seasons, with his existence being largely ignored, Arashi finally hands him some salt in the last episode of Akinaichuu.
Onee-sama: Kaja gives sort of that atmosphere to Jun.
Scenery Censor: Leaves fall very conveniently to obscure Jun's gender.
Second-Hand Storytelling: Episode seven of Akinaichuu is a time-travel heavy episode that takes place completely in the present day, with the audience only hearing of what happened three days ago.
Selective Obliviousness: Hajime is unable to realize that Jun is a girl... despite groping her breasts couple of times, seeing her half naked and swapping bodies with her at one point. In the Hot Springs Episode, he sees her completely naked and still doesn't catch on.
Shout-Out: It's a Shaft series, this is expected. Customers that look like Tenma and Harima can be seen seated in the Hako-bune in one episode, Yayoi and Kanako have a regular segment that alludes to other anime series, and the opening is a barrage of references to old CD covers.
The show subverts its own running gag when, in episode eleven, Master is able to correctly guess the anime (Glass Mask) before Kaja even gets the first sentence out.
Stable Time Loop: There are quite a few, with the first episode having an increasingly complicated time loop. Everything from the events of the first/last episodes of the first season all the way up to how Arashi and Hajime met.
The Straight Man: Jun and, to a lesser extent, Kaja, yes, a crossdressing girl and a ghost.
Surreal Theme Tune: Second season opening theme makes less than no sense and has no relevance to the series itself.
Sweet Tooth: Kaja, who's easily coerced into doing things for cake and takes her pudding very seriously.
Test Of Courage: One of these takes place at the hot springs. Yayoi is terrified of ghosts despite being one herself.
Timey-Wimey Ball: A good part of episode nine is dedicated to Hajime and crew trying to untangle the timey-wimey ball that makes up their universe. Mostly in the matter of "What happens to the timeline that was when we change it?" This isn't made any easier by the fact that Master has zero understanding of how time travel works. She thinks that leaping back ten years would make her into a sexy teenager again, when it would really just set the current her in a different time.
Title Drop: In the penultimate episode of Akinaichuu, in the middle of an impassioned speech about helping those who come into the Hako-bune, Arashi works the series' name in.
In several episodes in the first season, the series' name is written across many places here and there. A particularly prominent time is during Kanako's and Hajime's argument in Yayoi's house during episode 10.
Transformation Sequence: Arashi and Kaja change into their schoolgirl uniforms just before they time leap. The sequences are usually short, but always flashy.
Tsundere: Jun is a B type. Anyone at her place would run out of patience around Hajime.
Yamato Nadeshiko: Lampshaded by the Master in reference to all four girls but only Kaja, the German, fits perfectly. Arashi not so much, Yayoi is more of a Kawaiiko, and Kanako can be called the opposite of it.