Sakuya Izayoi

Species
Human (not native to Gensokyo)

Abilities
Space-time manipulation.[1] [2]

Age
Said to be 10-20 years old[3], implied to be way older[4].

Occupation
Maid

Location
Scarlet Devil Mansion

Personality
Sakuya tends to be a little spacey, but it's unknown if its just an act. She's polite and pleasant towards to her mistress Remilia Scarlet and those she's close with, such as Patchouli Knowledge, while being less formal with other people. With those she's frequently annoyed with, such as Marisa Kirisame, she can be somewhat harsh and direct with her insults and smack-talk, especially during duels. She seems to possess a wry wit and delivers comebacks stoically.

In connection with her Age
As for her age, ZUN directly stated that "she plays the role of a human maid about 10 to 20 years old"[8] and "perhaps she is a character in her early teens[9], and in Perfect Memento in Strict Sense, according to Hieda no Akyuu, "she claims to be in her late teens", but acts with the mannerisms of someone and the level of her ability seems like that of a human that's been living for more than a hundred years. According to a quote from Remilia Scarlet and Sakuya's ending in Imperishable Night (Good Ending #3), Sakuya has been working at the Scarlet Devil Mansion for so long, Remilia doesn't feel it fitting to call her human. With a comment like that, it seems safe enough to assume she has been at the Scarlet Devil Mansion for an extremely long time.

Ability
Manipulating time
Hieda no Akyuu believes Sakuya has managed to live so long while still looking like a teenager by manipulating time. It's true that Sakuya can increase the speed at which something ages, such as making bamboo flowers bloom instantly in Marisa's A ending of Embodiment of Scarlet Devil, even though this would normally take sixty years. It seems safe enough to assume she can decelerate aging for a specific object, too.

According to Sakuya, her ability to stop time is actually her moving at extremely high speeds with no mass, and she commented that she lacks the ability to stop the progression of someone else's time. While it's possible that this could have been an effort to make Reimu leave and rid the Scarlet Devil Mansion suspicion of kidnappings, there is no way to prove otherwise.

She possesses a great amount of silver[5][18] throwing knives and is skilled at handling them, and with only her ability to manipulate time[19], she is skilled in conjuring knives from nowhere.[5][20][21]

Her throwing range is said to be 20 ken (about 36 meters or 39.8 yards) and has the accuracy such that she is able to strike an apple on the forehead of a fairy. A portion of her throwing-knife ability is within her cooking ability and therefore is very skilled at cooking as well.[20] She also is able to conjure knives in battle as danmaku as well. In the games, despite Sakuya showing to make knives appear mysteriously when time is stopped, her artwork in The Grimoire of Marisa shows that she's placing the knives physically.

Design
Her appearances in Immaterial and Missing Power, Imperishable Night and Scarlet Weather Rhapsody are very similar. Sakuya is seen with grey eyes and once again wearing short sleeves. She appears to the have a thin black ribbon on the maids outfit. However in Imperishable Night she holds a knife and an old stopwatch, where as in Scarlet Weather Rhapsody, she has three knives and a plate with cups and a teapot on it. The colour of her eyes changes with each work.