Well, there is one he haven't tried

Wait, would that actually work? How exactly would he own himself? He look at his own arm and gave a thought.

Well, couldn't hurt to try right?

Not seeing much of a drawback of not trying, he pulls his sleeves to show his forearm, he wrote it down with his marker, baring no mind to onlookers wondering why he is writing his own arm.

Hyoudou Issei

There, that should do it.

He waited for a few seconds to see if anything upon, yet the students paid no mind to him and are just going about on his days.

"Hmmm, I don't feel anything." There doesn't seem to be any effect he is aware of, he doesn't feel like his mind being overwritten(thank god for that), and the people don't seem to react as much.

"Maybe its because I didn't do anything yet."

Wanting to see if it work at all, he tests it by walking towards a student passing by.

"Hey what do you think of this?" Issei he shows his forearm, making sure he can see the letters.

"Huh? What else, your name, your body, you own it after all," The guy simply walk away.

"So it does kinda work." The fact he stated about owning his own body rather than something along the shows that the effect is still there.

But exactly what would that do? It's not like he can do what others do by owning his own body, he already did own it, and doesn't need a tag to prove it.

Though maybe they won't try to hurt him? As it is his Ownership, an enemy won't try to harm him at all? Just like how the most of them won't try to destroy the property at all. That would be a great repellent.

"Though I could test that later," Well, its good to know that it kinda works on himself, but to what extent he ain't sure.

Suddenly, a light bulb of an idea appear in his head.

"Hmmmm, maybe," add something extra.

Hyoudou Issei's presence

"I want my presence to be unnoticeable by anyone!" Issei said to himself, he looks around to see the reaction of others.

_"Did it work?" _Man is this hard to test out.

"Let's try it out," He spot a girl walking by, there, he waves his hand in front of her face and sure enough, she shows no sign of responding.

"She really didn't notice me," with that knowledge, he flip her skirt to just mess with her.

"Kyahhh!" The girl squeak, and turn around glaring at the male student behind her who looks confused.

"You!"

"Wait a minute, it wasn't me!" The man does not know why he is the victim.

"Well, that guy is unfortunate," Issei said, as the male student tries to explain himself, Issei grins in excitement.

"Hehe, it actually work!!" This would make a great espionage skill. He could just sneak in the church and write his name.

Or just overall peek on the bath, sometimes, being allowed to be in bath is great an all but he prefers the excitement of females unaware of them being watched like back in the days.

What else could he do? Maybe he can break the limit of his body and do superhuman stuff(though that may be dangerous, since it might tear his muscles). Is this what the voice meant about not using most of the Ownership?

"Oooooh, this is going to be great