The school shall be his testing ground

Today, Issei simply chose to practice his power, school being the last thing on his mind, or the learning aspect of it.

Well, he is going to learn something that's for sure,

"Haha, forget school, I have to practice more on this power." Issei thought as he began to practice his power.

He very much easily took control of the entire school, it was surprisingly easy, with Rias and Sona under his control he simply just make himself having attendance even he is not in class.

Though only for today at least, as much as he does not enjoy school, he knows that grades are important and that knowledge are power, he would need it to achieve his harem

And so, he kept practicing ability he would be called Written Ownership(original I know). Issei tested from writing his name in a different language, and groping boobs, to see if he could just control specific body part(and groping boobs).

It was a very scary discovery for him to actually able to even own the mind of someone, he tested on the two Kendo girls and wrote down the specific Hyoudou Issei's mind and they basically became emotionless dolls, the effects would even work on places.

The two did not respond and do practically anything with that expression (of course he kept groping their boobs), and he could even alter the minds and memory too, he tested by making her forgot what she has eaten before, and even change her personality temporarily. He reset it all back afterward and the two were left confused.

It was a very scary ability and he doesn't think messing with the mind is a good idea(to an extent, his power is still mind manipulation after all), he would refrain from altering too much on the psyche. At least it would be convenient to capture enemies.

"Oh yeah, there is definitely going to be unwanted people coming after me huh." Issei thought about it. This is also another reason to practice his power. There is definitely going to be some unwanted visitors. Rias and Sona told him that Sacred Gear users tend to be sought out due to how powerful some of them can be, and sometimes in a forceful manner. And while he may not know what exactly is considered the top tier, but he can be sure having the power to literally own people is probably a very powerful one.

"Well, if they do, I could just control them, and if they are girls-" a lecherous grin formed at the thought.

Now then let's see the list of what he can do with his Sacred gear:

1) He can own anything so long as he wrote his name own it including people(obvious enough)

2) The people would consider you the owner of what you write, and would accept punishment for using it without "permission" though how far he still hasn't seen yet. He doubt people would kill themselves, and he is not likely to try that out.

3) The ownership will be gone if the name is removed, though the previous order seems to remain until you say otherwise.

4) You can be more specific on what you exactly own. Like a certain body part for it to be potent. And it doesn't seem to need for that person that actually looks at the writing to actually be affected by it.

5) The range of ownership extent indirectly even if it is technically separate so long as it's specific.

Example: You would own the room even if the name is written on the chair (Hyoudou Issei room) so long as the chair is in the room itself.

6) The consequence is nullified as people don't seem to hold a grudge(well they probably do) Most likely the reason that he owns the room and was adding orders at that time.

There is probably more that he hasn't discovered yet. But hey, its why he is experimenting,

"Now then, which oppai should I fondle next," Issei thought as his face is smothered by boobs of a certain background female student.

Oh yeah, Did we forgot to mention that?