Eye Jars and Implants

Eye Jars

A taken eye goes into a jar named "<Owner>'s <Eye>" in red (for example "Tito's Mangekyo Sharingan (Obito)").
Items: the Sharingan jar (used for the Sharingan and every Mangekyo), the Byakugan jar, the Rinnegan jar, and a plain "Eye in a Jar". All stack to 1; the dojutsu jars are of epic rarity.
The jar remembers which socket the eye came from ("Left eye" or "Right eye" in the tooltip) and which techniques the eye carries.
Tooltip: "Use to implant it: in an empty socket, or pick one of your eyes to take out for it first."

Which Techniques an Eye Carries

From the victim's learned nodes in that eye's own tree, every one this eye can use: the eye itself, every technique either eye can cast, and Kamui (right) or Kamui: Warp (left) only if the eye came from that side.
Never Susanoo, since it needs both eyes.
Example: Obito's right eye carries Mangekyo (Obito) and Kamui; his left eye carries Mangekyo (Obito) and Kamui: Warp (if he had learned them).

Implanting: the Minigame

Right-click with the jar. A left eye can only go in the left socket and a right eye in the right. If that socket is empty, the implant minigame opens with three steps:

1. Steady: the eye trembles in your fingers, following the mouse with a tremor that gets worse with each slip. Keep it over the socket (within 55% of the socket's radius) until it has seated for 2 seconds. Straying only loses a little progress; straying for more than 5 seconds in total is a slip.
2. Align: the eye turns on its own as it settles. Turn it (scroll wheel, 9 degrees a notch, or hold A / D, 80 degrees a second) so its mark meets the socket's mark (within 12 degrees), and hold it there for 1.5 seconds. Taking longer than 20 seconds is a slip.
3. Seal: three stitches of chakra. A needle sweeps back and forth, faster with each stitch; click as it crosses each green mark (within 6% of the bar). A miss is a slip.

Slips: each slip deals 3 damage and 1.5 seconds of blindness, flashes red, and restarts that step. After three slips the eye goes back in its jar (an abort, with the same damage).

Success: the eye is implanted in that socket. You get 3 seconds of blindness and "Implanted: <jar name>", and the jar becomes an empty glass bottle.

What Implanting Does

The socket is filled (no longer empty), and that socket's Mangekyo blindness resets to 0%: the new eye sees clearly.
Every technique the jar carries is learned, marked as granted by the implant. The eye's own opening technique is always included.
An implanted eye has only the techniques that came with it. If you have an eye only through an implant, the rest of that eye's tree stays locked to you.
Implanting any Sharingan or Mangekyo gives the full 3 tomoe at once (Sharingan stages 1-3 appear on the wheel).

Swapping an Eye

Using a jar when its socket isn't free opens the swap screen: pick which of your eyes to replace, each shown as it is now. A jar holding a left eye can only replace the left one, and so on. "That eye comes out first (into a jar). Then use this jar again to implant the new one." Esc cancels.
The same solo duel (8 rounds) then runs on that socket, without a scalpel; you must keep holding the jar.
Success: "Your <eye> is out, in a jar. The socket is free: implant the new eye." A removed dojutsu goes into a jar. Then use the new jar again to implant it.
Failure: "Your hand slipped. The eye is still in." and 3 damage.

What an Empty Socket Means

Losing an eye empties that socket only for that eye (and the Sharingan it grew from):

Taking a Mangekyo empties the socket of that Mangekyo and of the plain Sharingan. Another Mangekyo you own is NOT touched: it still has both eyes. For example, someone who owns Itachi's and Obito's Mangekyo and loses the left Itachi eye can still open Obito's Mangekyo with both eyes and use its Susanoo.
Taking the plain Sharingan empties the socket of every Sharingan (and so every Mangekyo).
Taking an implanted eye, a plain eye, or an eye from an already-emptied socket empties the socket of everything.
When an implanted eye is taken, the techniques it brought are forgotten, unless the other socket holds the same implant.
If no socket holds the open eye any more, it closes. If a Susanoo is out and one of its eyes is gone, the Susanoo is dismissed.
If both sockets for an eye are empty, it can't be opened ("blind").
What each socket shows, in order of priority: an empty socket; an implanted eye; your open eye if it's your own; otherwise the last eye you learned yourself (a Mangekyo before the plain Sharingan); otherwise a plain eye.

Implanted Eyes in Practice

A thief with an implanted Mangekyo can open it (its upkeep and blindness apply), use its carried techniques with that socket, and see through walls, but can never use its Susanoo and can't learn its other nodes.
Side rules still apply: an implanted right Obito eye can use Kamui (right) but not Kamui: Warp (left).
The implanted socket starts at 0% blindness.