He couldn't fathom why it fascinated him so much. It was such small thing and decidedly beneath his notice… normally. But it called into question something that he may have over looked upon his own person and that was not acceptable.

It had started a few weeks after Rin first came under his protection. Jaken had been her primary care provider at first with Sesshomaru merely being their guardian. But that had begun to change. He found himself being slowly accepted by Rin, her trust encompassing more than just her reliance on him. His own instinct had allowed her to follow him, but at first, she was barely noticeable. Anything she needed or wanted was addressed by or through Jaken and it had been to Jaken she had spoken her first words.

Later, when Jaken has once again resumed running the many torturous errands for Sesshomaru, Rin had begun depending on her "Lord" for all the things that Jaken usually dealt with. Protecting her during her bathing ritual was one of them.

The human form was never really of any interest to Sesshomaru and the form of a little wraith of a female was even less so. And so it stood to reason that he hadn't noticed anything to give him pause or cause him to consider their intricacies as he'd never sought to discern them. But to his surprise, and later chagrin, he did observe something upon Rin's person as she was exiting the springs one day that shook him quite particularly. There was an… indention in her midsection. It wasn't bloody, so it clearly wasn't a wound, but it was there nonetheless. Maybe it was a healed injury that she had sustained during her time at the village that mistreated her?

He had immediately asked her about it, "Rin what is the meaning of that."

Clearly confused she looked down to her belly. "What do you mean Sesshomaru-sama?"

He gestured vaguely toward her abdomen.

"Rin's bellybutton?"

Sesshomaru blinked. Bellybutton? What a ridiculous term for a former injury. "How did it happen?"

She cocked her head to the side endearingly and shrugged. "Rin has always had it."

That was interesting. "What is its purpose?"

At this Rin's eye widened. "Rin doesn't know. It's just always been there."

That was interesting. Sesshomaru had always assumed his own humanoid form was perfection in and of itself; excepting his missing left arm. But strangely, he did not possess this bellybutton that Rin's small body harbored and it brought up two disturbing questions; did all humans have one and where was his own?

Though he had much more important things to ponder, this one thing would not leave him alone. It seemed to only escalate after his own entourage joined that of his younger half-brother. The human women took over the responsibility of bathing his ward. Their propensity for bathing often did little to alleviate his new found obsession over the human midsection. It was maddening. It led him to act out of character.

"Inuyasha."

The half-demon slanted a glare his direction. "What?"

"Remove your clothing."

That got a start. "What? NO!"

"Now."

The whelp was as red as his firerat. The monk joined in. "Sesshomaru-sama, I don't mean to be rude, but that is not a request any male takes lightly. Can I inquire the reason?"

Sesshomaru raised his nose. He wouldn't explain himself. "No."

"Well I aint doing it. You can go fu-"

"Ah, ah, Inuyasha. Language. There are children present." The monk interjected while nodding his head toward Shippo.

"Hmmph. Crazy bastard wants me to- hey where are you going?"

Sesshomaru didn't bother to answer. He gracefully exited the camp in the direction opposite the hot springs. He did not want his purpose to be thwarted. He was determined to put an end to this… obsession.

Circling around and masking his aura and scent, he stealthily approached the springs and immediately sought out the forms of the females of the group. Curses. The area in question was below water level. Rin was happily chatting and swimming while the two older women went about their bathing routine. Gods, would they ever quit talking and just show him what he needed already? His patience was wearing thin. If they did not reveal themselves soon they would force his hand and he'd drag them out; likely kicking and screaming.

Finally after what seemed an eternity they exited the spring and his suspicions were confirmed. They all had the indention. What was its meaning? He was determined to find out. He gracefully dropped into the circle of the women.

"Sesshomaru-sama!" Rin greeted happily, oblivious to the distressed cries of her equally under clothed companions.

It took only moments for Inuyasha to come crashing through the trees.

"What. The. Hell. Sesshomaru? Leave." He greeted, Tetsuiaga brandished.

He turned to the Miko who, though bright pink with embarrassment, would likely give him the answer he desired.

"Miko. Explain."

She squeaked and retreated even further behind Inuyasha, leaving only her head visible. "Explain what?"

Sesshomaru vaguely gestured toward his midsection. He received three equally confused stares.

"Oh!" Rin piped in, the only one not appalled by the situation. "Sesshomaru wants to know what a bellybutton does!"

The look on the groups faces had Sesshomaru's ire rising. Why the credulity? It was a perfectly sensible request.

Inuyasha, as always, was eloquent. "Huh? Is that why you wanted me to get naked?"

Kagome squeaked again. "What? What is going on?"

By this time the monk had arrived. "I believe I can explain. With the help of my lovely Sango of course, who, I must say looks particularly ravishing."

Sango glared. Clothed in only a towel, her efforts were less than convincing. "Monk, when I get back to camp I'll-"

Sesshomaru did not have time for this. "EXPLAIN." He interrupted.

"Humans are born with them. They are attached to their mothers at birth. At such time the cord is severed and tied, creating a type of indention or scar. Do half demons have them Inuyasha?" The monk inquired.

Inuysha glared and crossed his arms, refusing to answer.

"Yes he does," the Miko replied absently causing Inuyasha to turn red. "Wait, does that mean Sesshomaru doesn't have a bellybutton?" She asked a little too eagerly.

The round of stares focused on him. His eyes narrowed into a look that screamed death.

"I am perfect." Sesshomaru proclaimed, daring anyone to deny it.

"Undoubtedly Sesshomarua-sama." The monk soothed. "Kagome, let me explain. Sesshomaru is a Taiyoukai. As such, they are of this world but not of it. When Sesshomaur's parents," he waggled his eyebrows suggestively, "procreated, they likely did so in their demon form. Taiyoukai when they are born, just become. A union between the two is little more than two very powerful aura's merging and creating a wholly separate one. In this case, Little Sesshomaru." Sesshomaru growled but it did not stop the monk from tossing him a cheeky grin. "As he was not born, he has no bellybutton."

Inuyasha grinned as well. "Ha! What a freak!"

"Whelp-" Sesshomaru began as he advanced.

"Now now, Inuyasha. Sesshomaru is no different from any other Taiyoukai."

That placated and irritated Sesshomaru at the same time. Of course he was different. He was superior. But it stopped his advance.

Giving the collected group a dismissing nod he leapt to the sky. At least he had his answers. The bellybutton conundrum was solved.