
It would be cool if kumono spend a century at the cave but not like this manga gonna take a century of the adventures inside the cave, anyway with a lot of experience from the labyrint he would meet a human on the way out to an exit and formed allaince it could be the demon king. Interesting rght?

Low level spoilers from the novel...
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...She doesn't spend a century (she finds out she was in there for less than a year iirc), she does meet more humans...which mostly does not go well. She tries to play nice. Then they mess with her webs. She worked hard on those webs.
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I won't say anything about the demon king.
http://www.mangago.zone/read-manga/dalkomhan_namja/mf/c001/18/
Big body, small heads.