One Week Friends is available to stream on Crunchyroll, HiDive, and VRV.
Anime has a tendency to pull some weird concepts out of its collective hat.
See, for example, the the buddy comedy film where Buddha and Jesus share an apartment. Or the show about an after-school club for piloting (remarkably accurately-drawn) tanks as a sport. Or the manga about a retired yakuza thug, turned into a house-husband who becomes intensely dramatic over household chores.
(Please see that last example. It’s called Gokushufudou, and it’s fantastic.)
Then there’s One Week Friends, which is less overtly odd insofar as other stories have taken memory loss as a serious, dramatic subject. But the female lead in One Week Friends (because tragedy disproportionately targets Japanese teenage girls) has a hyper-specific form of amnesia, promptly forgetting the last week’s worth of memories relating to extra-familial people at 12:01 AM every Monday morning.
It sounds more like the main mechanic of Majora’s Mask than any realistic scenario.
And it makes a very useful story right now, oddly enough.
This Thing Is Neat 