An imprinting egg is a special type of egg created and used by the Phoenix People to make whomever they choose their devoted slave.
The eggs look like normal chicken eggs, but when violently broken open, will unleash entangling threads that envelop the target and cocoon them within a giant, human-sized egg in seconds. When this giant egg is hatched or cracked open, the person inside will imprint on the first person they see in a similar manner as a newly hatched chick, regarding this person as their master. They are utterly loyal to this person and will carry out their wishes without question.
Imprinting eggs can cracked open like normal eggs without any ill effects, as Plum did this to show that they are inedible. When used against a target, several eggs are usually thrown to insure success. The gestation period is very fast, as a target only needs to be successfully enclosed with an egg to become a potential servant. However the eggs can also be hatched by heat. The Phoenix People are revealed to keep large numbers of the eggs in storage until the servants are needed while refrigerating unused eggs.
The eggs were first used by Koruma and Masara to capture Shampoo when she was by herself. They took the Shampoo egg to Kiima, who lay on it to hatch it by herself, ensuring that Shampoo would become her devoted servant. She then ordered her to capture all the pieces of the Jusenkyo map, which had been split into five pieces, one in each of the cursed characters' hands. Shampoo successfully captured three pieces after being given her piece and got Ranma Saotome's piece last, which revealed to the others that she was under some form of mind control.
At Ho'o Peak, Ryoga Hibiki, Mousse, Plum, and Genma Saotome fell into a storage room full of giant eggs. Genma stole a sackful of unused eggs from a refrigerator, thinking that they were normal eggs. When Ryoga cracked open one giant egg, an elderly birdman emerged and called him master, offering to serve him. Mousse recognized this as imprinting, explaining why Shampoo, who he knew so well, would willingly serve Kiima all of a sudden. After the group escaped Ho'o Peak, they discovered that the stolen eggs were inedible.
When they later attempted to enter Jusendo through the employee entrance, they were set upon by Shampoo, who was guarding it. She was using special chúi that had hollow spheres, each containing several eggs. During the ensuing fight with Ranma, Shampoo kicked off one of the spheres which split open when Genma struck it, releasing the eggs and cocooning him. She then tried to break it open to make Genma her servant, but Ranma broke it first. However she punched too hard, knocking Genma out, and when he was woken up by slapping, Shampoo was able to jump onto Ranma's head and become the first person Genma saw, becoming his master.
Ranma was later captured by Shampoo after he had damaged the Phoenix Spout with the Gekkaja. When he came to she offered to trade him Jusen water to restore Akane Tendo to human size again in return for becoming her slave through the imprinting eggs. Ranma was able to knock the eggs out of her hand and catch them with his mouth, spitting them at Shampoo. However she evaded the eggs and the bottle of Jusen water was broken. When Ranma told her that he wanted to see her naked to see if she had more eggs, Shampoo revealed that there was a pair tucked between her breasts when she stripped her blouse off. She threw these at Ranma after Mousse and Ryoga broke into the room they were in, but he was able to catch them with her bra and throw them back, and Shampoo was cocooned for a second time. Mousse stopped Ranma from breaking the Shampoo egg and Ryoga realized that he was trying to be the first one that Shampoo saw so that she would be his. Mousse was sorely tempted by the prospect of a Shampoo completely devoted to him, but realized that if she loved him this way that it would not be because of his own merit and would haunt him. His hand was forced when the wall collapsed and a section knocked him onto the egg, cracking it. Mousse decided to forego his chance and placed a mirror in Shampoo's hand, making her see her reflection when she emerged. This released her from Kiima's control and returned her to normal.
Genma was later released from Shampoo's control when she told him to do whatever he wanted following Ranma's climactic battle with Saffron.