Hunter x Hunter: Season 1, Episode 22
Gon, Kurapica, and Leorio arrive at Kukuroo Mountain only to find out that they cannot get close to the Zoldyck family estate. The Zoldyck family owns the mountain and all of the surrounding forest and the entire region is gated shut. There is a guard outpost immediately outside of the gate, but instead of serving as a guard, the man working in there actually cleans up the mess created by the watchdog whenever there are intruders into the grounds. Gon, unwilling to give up on "rescuing" Killua, learns from the gatekeeper that the actual door is the massive stone gate and anyone who enters via that path will not be attacked by the watchdog. Leorio tries to pull and push on the gate, to no avail. The gatekeeper informs them that the gate opens up different amounts of stone slabs based only on the strength of the person; however, the least amount of strength anyone needs to open the smallest portion of the door requires two tons of strength on each side.