Thats not really a good way to recognize you are in the genjutsu. What if your opponent had Wood Release? Better yet, what if your opponent was Yamato. He's been known to create waterfalls and trees would be a breeze. Just because you DIDNT feel it doesnt mean he couldnt have made it.
So for a Genjutsu like this one, you want to go based off of things that you do feel, or you simply ignore it. For example. Like I stated above, if your opponent were to use this jutsu to make everything look the exact same but trap you in a swamp. You wont be able to see it, smell it, taste it or hear it. Everything in you is telling you that nothing is happening. However you can FEEL that you are sinking. You use that feeling to get you out of the genjutsu.
Anything else that is quite harmless to you or at least appears to be, you ignore for the time being. However just because you are ignoring it, doesnt mean you have to ignore it. Your opponent isnt going to just put you in a genjutsu and end their turn. So when they attack you, you have three options to get yourself out of a genjutsu.
A. Kai......this will not work, as you technically do not know you are in a genjutsu, so how would you know to use it.
B. Surge of chakra.....And I can't stress this enough, but FULL BODY surge of chakra. Techniques that require chakra to completely course throughout your body. This can be done with Nagashi, Added Weight technique, etc.
C. Pain....The last resort. Stabbing yourself with a kunai, using a forbidden rank technique, Biting your tongue OFF (not entire thing but a piece. You will also have to find a way to stop yourself from bleeding or you will die from blood loss....not recommended to do but sometimes necessary. The best way for you to do this, depending on how your opponent attacks you, is to use Earth Release Hardening Technique. This creates a protective layer as well as allowing you to create weapons. You then create a small weapon and stab yourself somewhere that will cause you pain but not hinder your fight. This is also good if you are fully paralyzed making option A completely impossible anyway.
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Genjutsu: Kahen Tonsou (Illusion Technique: Flower Petal Escape)
Rank: D
Type:Supplementary
Range:Short
Chakra Cost:10
Damage Points:N/A
Description: The user vanishes in a whirlwind of sakura petals.
Make me see as if you were disappearing in cloud of flower petals that form a swirl (using the regular genjutsu basics)