Key the Metal Idol is often an intriguing puzzle box, but sometimes it needs to build the box first. This is the primary purpose of CURSOR I, along with establishing Sakura both as Key’s primary support and as the most sympathetic character in the series.
It also presents a challenge as to what details to capture when writing the synopsis: my memory for what details will be significant later  is not the best as it has been several years since I last watched Key end to end.
The tag is a flash back to Sakura leaving Mamio Valley before Key enters Sakura’s apartment in the present time. This is when the credits roll.
This episode picks up immediately where START UP left off with Sakura and Key fleeing from Tamari and the muscle. On arriving home Key is showing no reaction whilst Sakura collapses out of breath. To recover from the exertions of fleeing Tamari, a very sweaty Sakura heads for the showers.
One thing I am finding somewhat annoying on this viewing is the extent of the fanservice. To quote the TV Tropes page: “Sakura and Key apparently need to shower often”, and Sakura’s character design does tend towards to Ms. Fanservice. 
Tamari uses the pizza delivery scooter to start tracking Sakura down. Meanwhile Key is using a device to measure her vital signs that produces small tablets as a food substitute .
Sakura heads out to her second job and invites Key to come along to hear her story. As they walk to work Key tells Sakura about the 30,000 friends. Sakura is revealed as a nice person here, promises to help, and offers Key her apartment as a place to stay. They are being followed by the muscle, as Tomoyo is lurking in the background .
As Sakura works in a video store Shuichi Tataki enters with a concert video of Miho Utsuse, the idol seen briefly in the previous episode. Tataki is the president of Miho’s fan club and is shopping the video around.
As the video plays someone Key is fascinated and someone is grabbing a lot of videos off the shelves. The mystery person is revealed to be the muscle and asks Sakura to step outside. Sakura is confronted by Tamari on Sakura’s scooter. Tamari is here to make an offer to Sakura, but Sakura isn’t buying it. Even when Tamari offers triple Sakura’s salary from her three jobs, Sakura is rather firm  in her refusal.
This is both a test of character for Sakura’s part, and a test of Key’s understanding of the events of START UP. Sakura passes with flying colours, Key… doesn’t.
As the threats start up, Tataki intervenes and proves to be rather better than the muscle. Tamari has a painful time as the scene switches back to the concert video.
This scene is primarily intended to establish Tataki as a nice guy and a martial artist. It works well enough, especially as Tataki senses Tomoyo lurking in the shadows.
Back home Sakura and Key discuss possible options to get Key her 30,000 friends, and Sakura has a troubled night sleeping. This is where Key again fails to understand the implications of Tamari’s job offer and her obtuseness does contribute to Sakura’s irritation.
Meanwhile in Mamio Valley Sergei is searching Dr Mima’s house which he had apparently ransacked earlier. There are hints that Mima’s death was not the accident previously implied. Sergei also notices a photo of Key and Sakura, and damages it by spitting a marble at it with a fairly impressive muzzle velocity. There is no indication of where the marble is coming from .
As Key wakes up she finds a note from Sakura telling her to take a shower. The scene clearly shows that hours pass as the shower continues to run.
At the concert hall Ajo is supervising the set up of Miho’s next concert and orders the removal of the elaborate staging. Miho is also unwell it seems, and Ajo is informed of Sergei’s return.
Once Sakura returns home Key awakens from her collapse in the shower, and Sakura is really worried about what happened. There is also a semi dream sequence here showing a long haired girl sitting in the rain, but it isn’t Sakura: the hair is slightly differently styled and brown where Sakura’s is black.
Next up is a brief encounter between Ajo and Sergei in some strange surrounds – creepy dolls, medical equipment, red lighting.
Back with Sakura and Key, Key is mesmerised by the concert video and starts moving towards the screen as Miho appears to be reaching out from it. One interesting aspect is that Key is wearing headphones and viewer hears nothing: the viewpoint is external to Key, and the silence makes this a fairly otherworldly scene to watch just before the credits roll.
CURSOR I is a set up episode that works as part of a story line but not as a standalone. There are hints of things to come, but it isn’t really a complete story in and of itself. START UP had the resolution of Key coming to Tokyo, and meeting Sakura, but CURSOR I is only hinting that Key should look towards Idol Singing as her path to 30,000 friends.
Day 1 – START UP
Day 2 – CURSOR I
Day 3 – CURSOR II
Day 4 – ???
Day 5 – ACCESS
Day 6 – SCROLL I
Day 7 – SCROLL II
Day 8 – ???
Day 9 – RUN
Day 10 – GOTO
Day 11 – RETURN
Day 12 – ???
Day 13 – BUG
Day 14 – SAVE
Day 15 – VIRUS I
Day 16 – ???
Day 17 – VIRUS II
Day 18 – SYSTEM
Day 19 – EXIT
Day 20 – Looking Back at Key The Metal Idol
- Announcing Twenty Days of Key the Metal Idol (piratesobg.wordpress.com)
- Twenty Days of Key the Metal Idol – Day 1 – START UP (piratesobg.wordpress.com)