Short Mission 6

Yuri drops to the ground while he and Lieutenant Chadwick Curtis are chasing a suspect, letting the man slip away. Blaming a cold, Yuri rests at an apartment and explains that his immune system crumbles whenever he dwells on Yor being gone, as she currently is on a work trip. The Lieutenant brushes off his apology, orders him to rest, and heads out for medicine, agreeing to pick up a particular herbal tea brand on the way.

Feverish, Yuri sinks into a memory that resurfaces every time he falls ill. As a small child with a fever, he watched Yor pour everything into nursing him and overdo all of it: piles of blankets, home remedies like a green onion wrapped around his neck, and foraging runs through the forest for anything she thought might help, taking bee stings and felling a boar along the way. Her reckless devotion convinced him to build a strong, healthy body so she would never need to worry. He told her he was lucky to have such a sister, she answered that the feeling was mutual, and her plea that he stay healthy forever fed his hope that the world would grow kinder for her. He even praised her herbal brew while immediately vomiting it up, insisting its strange effects had driven the cold out, which delighted her.

Yuri jolts awake in a cold sweat just as the Lieutenant returns with the requested tea and warns him about its notorious taste. Yuri wants it precisely because it comes closest to Yor's brew. He drinks it, throws it up, and springs up ready for duty, only for the Lieutenant to order him back to bed.

Yuri collapses during a pursuit and the suspect escapes. A fever flashback shows young Yor's chaotic caretaking and the sibling exchange that shaped Yuri's ideals.

In the present, he downs the awful herbal tea because it tastes most like his sister's and tries to return to work far too soon.

Short Mission 6 is a seven-page extra chapter of Tatsuya Endo's SPY x FAMILY manga, numbered 51.1 and released on August 23, 2021; Episode 33 adapts it, with Yuri and Chadwick Curtis on the cover. Its events fall between Chapters 44 and 57, while Yor is away aboard the Princess Lorelei during the Cruise Adventure Arc, though it is printed in Volume 8's final pages, after Chapter 53, a placement the anime also follows.