[[quoteright:300:http://static.tvtropes.org/pmwiki/pub/images/745601-one_week_friends_large_8411.jpg]]
[[caption-width-right:300:"Will you be my friend?"]]

->''The two of us became friends again and again.''
->''To create a memory of "a friend".''
->'' He swirls around the memory of "a friend".''
->''So that one day they can become "friends". ''

Manga/OneWeekFriends (Manga/IsshuukanFriends) is a {{yonkoma}} manga series written by Matcha Hazuki, serialized in SquareEnix Gangan Joker from January 21, 2012. It was first published as a one-shot manga in Gangan Joker's September 2011 issue. It has been collected in four tankōbon volumes as of December 2013. An anime television series adaptation by Creator/BrainsBase aired in [[Spring2014Anime April 2014]], and can be watched legally on [[http://www.crunchyroll.com/one-week-friends Crunchyroll.]]

High schooler Yūki Hase notices that his classmate Kaori Fujimiya is always alone, and seemingly has no friends. After approaching her and attempting to become friends, it seems that he is successful until Friday, when Kaori reveals that she loses every memory of her friends each Monday. Despite learning this, Yūki endeavors to become her new friend every week.

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!!''One Week Friends'' contains the following examples:

* AloofDarkHairedGirl: Kaori originally, though her aloofness was just an act to avoid making friends and potentially hurting them every week.
* ArcWords: "Please be friends with me". Hase said that phrase to Kaori every week.
* BookDumb: Hase, especially at mathematics. Saki too.
* BrokenBird: Kaori's condition started at elementary school and lasted for ten years, which has led to her developing a facade to protect herself from the pain of forgetting her friends.
* BromanticFoil: Shougo to Hase.
* BrutalHonesty: Shougo sees no need to sugercoat his words.
* {{Cloudcuckoolander}}: Saki has an odd, almost childlike way of looking at the world.
* DeadpanSnarker: Shougo.
* TheDitz: Saki's a bit of an airhead.
* EasyAmnesia: Kaori loses every memory of her friends each Monday.
** Notably, Kaori doesn't lose memory of those she ''does not'' consider to be her friends, which fortunately includes her family.
* FriendlessBackground: Kaori's amnesia, which she got in elementary school, causes this.
* GoodWithNumbers: Kaori.
* GrewASpine: The first [[AnAesop aesop]] Shougo taught to Kaori upon their first meeting at the rooftop.
* InnocentlyInsensitive: Because she is focusing herself to form platonic relationships, Kaori tends to overlook romantic implications her actions can have, causing Hase much frustration.
* MiddleChildSyndrome: Shougo's dislike against women in general is caused by his position as the only son in his family. His elder sister always bosses him around while his younger sibling cries a lot.
* MoodWhiplash: [[spoiler:The transfer student's appearance, relation and response to Kaori's past in chapter 14.]]
* NiceGuy: Hase.
** JerkWithAHeartOfGold: Shougo.
* OddFriendship: Yuki and Shougo. They're nothing alike, but the fact that they're on a FirstNameBasis with each other hints that they're actually quite close.
* ShipperOnDeck: Both Fujimiya's mom and Saki seem to ship Hase and Fujimiya.
* SupremeChef: Kaori.
* ThePowerOfFriendship: Hase's constant efforts to create good memories with Kaori, despite it being supposedly reset at the end of each week, is not entirely fruitless. Kaori began to retain bits and pieces of her memories even after the reset.
** Despite that, [[DarkAndTroubledPast certain]] [[PoorCommunicationKills triggers]] can undo all the effort put in by Hase.
* TheStoic: Kaori, although her stoicness is mostly a facade.
** Also, Hase's friend, Shougo.
* TastesLikeDiabetes: In-universe example. In episode 3, Shougo claims that Hase and Kaori's friendship is sickeningly sweet to the point where looking at them kills his appetite.
* TwelveEpisodeAnime
* WhamLine: Episode 9 has one.
-->'''Hajime to Kaori''': [[spoiler: You broke our promise. You traitor.]]
** Also chapter 17/episode 10 when [[spoiler: Saki says to Kiryuu: "Kiryuu-kun, we can be family!"]]
* {{Yonkoma}}