But the Triad of Gods—Nyarlathotep, Shub-Niggurath, Yog-Sothoth—or something darker, the Nameless Mist, or even the demonic lord Azathoth would be necessary.
Of course, his intuition and ability to lockpick mundane and mystical doors had already made him well aware that the door would budge with his current strength. It was a trap from the start. Hence, utilizing the door opening ability, the door opened smoothly.
Oh, and while his main body is kept in the Nutrition tank, Kuroto doesn't idle around. At that time, he transfers his soul into the Earth Chakra Nature Clone that has completely healed and works on cultivating it. After all, this clone wasn't fully cultivated, so that needs to be done as well.