In the Book
In the Movie
The first time Rita and Kiriya meet he is wounded/dying. Rita asks him if the tea served after a meal in Japan is free (this is a code phrase). When he asks if he is dying, she says yes but will stay with him until he dies; he is grateful. She will take his battery upon his death. She defends him from the Mimics so he can die unmolested. With the last of his strength, he kills a server Mimic with his pile driver.
Mimics are able to loop back in time to give them an advantage in the battle they repeat. A human who is in contact with a mimic when they initiate a loop, loops with them.
Cage is wounded and on the ground. Rita steals his battery and leaves without a word. Cage uses a claymore mine to kill a server Mimic that bleeds on him causing the loops to start.
Kiriya avoids battle after being immediately killed in loop #2; including going AWOL and suicide. He then writes the number 5 on the back of his left hand and vows to be a better soldier.
Cage is forced into the barracks as a prisoner his first several loops and is sent into combat without any training; a peril to his fellow soldiers. He gradually learns to fight better.
Rita's Jacket armor is painted all crimson so that she will stand out on the battle field. She uses a rifle and 200 kilogram battle axe made from armor plate.
Rita's armor has a small red design on the breast plate. She uses a small axe which appears to be a helicopter blade.
While killing Mimics with his battle axe, Kiriya hears Rita on the radio asking him how many loops this is for him. At the beginning of his next loop while exercising, he sees Rita and tells her the after meal tea in Japan is free; she knows he is caught in a loop.
Cage finds Rita on the battlefield and tells her he is looping. Right before they are killed she tells him to find her after he starts his next loop.
Rita knows how loops start and how to stop them. The military is working to understand the loops and better defeat the Mimics.
The military is not helping to find the cause of the loops and resists Rita and Cage's efforts to stop them.