If you start to gather natural energy, use curse seal, and then use that extra chakra to summon Shima and Fukusaku (the two elder toad sages) using the 7 chakra point combo (which saves 1 chakra use compared to summoning them independently for 4 points each) you have the option to use the amphibian technique.
When clicking on it, it then proceeds to auto-enter you into a 60 or so turn sage mode. However, since I never pressed enter sage mode, the gathering natural energy debuff is still active.
What in the actual what? The screenshot of the page that tipped me off that something was off shows the debuff and the buff active at the same time. My guess is that they are not supposed to both be applied to a character at the same time as each other.