Black box

Japanese: ブラックボックス（英語表記）black box

A device or system whose function is known but whose internal structure is unknown. In the case of electronic circuits, the process, circuit, or device that deals only with input, output, cause and effect without considering the internal structure. ⇔ White box.
2. By extension, a mechanism or system whose processing process is unclear to outsiders. Also, a specialized technical field that cannot be easily imitated by others. "Cost accounting is a complex intertwining of elements. Black Box It has become like this.”
3. Refers to an aircraft's flight recorder or voice recorder, as well as a shock- and heat-resistant box for storing such equipment.
[Additional information] Section by book title. → Black Box

Black Box [Book Title]

A novel by Fumiji Sunagawa. Published in 2021. Winner of the 166th Akutagawa Prize.

Source: About Shogakukan Digital Daijisen Information | Legend

Japanese:

１機能は知られているが、内部構造が不明の装置やシステム。電子回路などで、内部構造を問題にせずに入力と出力、原因と結果だけを扱う場合の、その過程や回路・装置。⇔ホワイトボックス。
２転じて、処理過程が部外者には不明な仕組みや機構。また、他人が簡単には真似のできない専門的な技術領域。「原価計算は複雑な要素が絡み合ってブラックボックスと化している」
３航空機のフライトレコーダーやボイスレコーダーのこと。また、そのような装置を保管するための、耐震・耐熱性のある箱のこと。
[補説]書名別項。→ブラックボックス