Short answers, pulled from the story.
The Hidden Dungeon Only I Can Enter is a Japanese fantasy light novel series about Noir Stardia, the third son of a minor noble, who discovers a secret dungeon and receives three powerful abilities from a legendary adventurer named Olivia Servant. The series follows his quest to grow strong enough to eventually free Olivia from the Death Chains that have kept her imprisoned for centuries.
The Hidden Dungeon Only I Can Enter was written by Meguru Seto and illustrated by Note Takehana. Seto originally serialized the story on Shosetsuka ni Naro starting January 2017, and Kodansha later published the first print volume on the 1st of August 2017 under their Ranobe Books imprint.
The Hidden Dungeon Only I Can Enter anime ran for 12 episodes, airing from the 9th of January to the 27th of March 2021, on the Animeism programming block on MBS, TBS, BS-TBS, and AT-X. The series was animated by Okuruto Noboru and directed by Kenta Onishi.
Noir Stardia has four abilities: Great Sage, which grants unlimited knowledge for a period but causes severe headaches after each use, and three skills bestowed by Olivia Servant: Create, Bestow, and Edit. The three skills from Olivia are powered by Life Points (LP), which accumulate through joyful experiences and, if depleted to zero, result in Noir's death.
The Hidden Dungeon Only I Can Enter anime was streamed internationally outside Asia by Crunchyroll, with Bilibili carrying the series in Southeast Asia. Crunchyroll announced an English dub on the 8th of February 2021, which debuted on the 26th of February.
The Hidden Dungeon Only I Can Enter manga, drawn by Tomoyuki Hino, was collected into twelve tankobonvolumes published from the 6th of December 2018 to the 9th of April 2024. The manga was serialized on Kodansha's Suiyobi no Sirius service from the 2nd of May 2018 to the 20th of June 2023, and Seven Seas Entertainment licensed it for North American readers.