Power-- Demonfication.

If you wish for it to be invisible or develop things invisibly, know that it is costly and people with an equal level of perception to your technique's level of effects are immune (look at Karasu vs Kurama) as an example in the actual series. But in your case, the invisible aspect is a supportive/supplementary technique, and not explosives (heh). 


Power Ceiling
Kami's power ceiling allows him to channel energy with the forceful power capable of overpowering actions beneath D class and defending actions equal to D class with the cost of 1 Effort. The giant manifested from his spirit energy will cost him 1 Effort to summon and maintain. It's maximum dimensions is 10 square meters high and wide. The giant is capable of building up a defense or an attack of C class with the cost of 1 Massive to summon and 2 Efforts for it to release offensive/defensive actions of C class power.

For Akki-Oni, at it's current level the duration is 3 posts with a 2 post cooldown. If you like, you can increase the meters to 10. This technique will cost him 2 Efforts per usage. Those with a Perception equal to or above him can see through its invisibility.

Know that, since the giant isn't a technique, it cannot be used in battle until you make it a technique. That will be when we can provide you duration/cooldowns for it. A lot of its ceiling is there for you to know about it though. Since it has the capability of being stronger than you (by +1 class level maximum), it will, obviously cost a whole lot more. I would recommend you to focus on your Control stat - that way you'd have enough reserves to control this thing that's naturally supposed to be beyond your control.

Edit on how you like it to function, and let's see how this can go. Looks good so far.