It was a gag present from Niou and Yukimura back in junior school, but after eight years Miffy had become part of Sanada's life. Sanada did very little in terms of taking care of it - his mother did that because it was a woman's job (or so his grandfather said) - but it had developed a fondness for Sanada in particular, following him and resting close to him when it was allowed to run freely. In Sanada's room, Miffy had free reign. It meant having to run cables higher along walls and making sure straps, shoelaces or anything chewable was not on the floor, but it wasn't too much trouble and Sanada was used to it. And he got to laugh at Niou when he visited and had the strap of his tennis bag chewed on.
Niou stuck a Miffy bandage over it. "My poor bag," he said, wiping a non-existent tear, "it's probably got rabies now."
Renji, not surprisingly, was the person Miffy liked best (besides Sanada). The affection was not entirely mutual, though; Renji did not enjoy being "stared at by beady red eyes." Sanada reckoned it was the beady part, not the red part, that unsettled Renji. But no matter how far he nudged himself away from the animal, the animal would follow him and sit down beside him. Sanada thought it was very cute, but he knew better than saying it out loud.
One of the few places Miffy was not allowed to go to was the dojo; it had a sacred status that not even cuteness could break. This was also the place where Yukimura made-out with Sanada for the first time, although they had not kissed before that or even told each other their feelings. It was of course not something that should be done in the holy dojo, but Sanada could think about very little when Yukimura's hands were under his hakama.
Miffy was there though, when they had sex for the first time. Yukimura tried to shoo it away, but it would not budge, and when Yukimura carried it out of the room, it kept running back inside before he could closed the door.
Yukimura laughed, gave up and pushed Sanada onto the bed.
Jackal and Marui hardly ever visited. The one time Marui saw Miffy, he tried to stroke its fur whilst asking (as a joke, Sanada hoped) if it was edible. Miffy bit him.
Jackal had a fear of rabbits due to childhood trauma. It seemed like seeing Marui being bitten intensified this fear; Sanada didn't ask. After that, whenever the pair visited, he made sure Miffy was locked up in its run, for the safety of all concerned.
Strangely enough (but why strange, Sanada could not say), Akaya loved Miffy. He had never visited Sanada's home until he was in senior high, but he squealed in delight like a small child when he saw the rabbit, picked it up more gently than Sanada had ever seen him done anything, and put it on his lap. Miffy tolerated Akaya. Since then, Renji developed a fondness for Miffy too, and liked to stroke it when it was sitting on Akaya's lap, his eyes not really looking at Miffy's beady red ones but at a pair that was full of awe and happiness.
(Sanada went on a family holiday once and asked Renji to take care of Miffy. When he came back, Renji and Akaya seemed to have gotten a lot closer. And Akaya visited less since then; it turned out he didn't adore Miffy as much as it initially seemed.)
Once, when Yagyuu visited to work on their group project, Miffy chewed on the strap of Yagyuu's bag, in exactly the same place where it chewed Niou's bag. Yagyuu was a bit annoyed, and Sanada told him to ask Niou for a bandage.
Sanada could hardly remember a time before Miffy.
"Oh- ow!" There was wincing and laughing. Sanada turned around and stroked his pet rabbit, which had just launched itself onto Yukimura's stomach. On the bed, Yukimura stretched out whilst making sure he didn't disturb the animal. "Miffy's a top."
Sanada raised an eyebrow, saying nothing.
"I bet he's a good top. You know what people say about pets and their owners?"
Sanada blushed, removed Miffy from where it sat, and proceeded to prove Yukimura right.