• 秘密ひみつ — secret
• 密室みっしつ — sealed room
• 密接みっせつ — closely related
• 親密しんみつ — intimacy, closeness
• 過密かみつ — overcrowding
• 厳密げんみつ — strict, precise
• 密談みつだん — private talk
• 密輸みつゆ — smuggling

The kanji 密 combines 宀 (roof) and 必 (essential), forming the image of a deep, secluded place — like a hidden chamber or inner sanctum. This conveys secrecy and compactness.

It gained special attention in 2020 during the COVID-19 pandemic, as the term “3密” (san-mitsu: closed spaces, crowded places, and close-contact settings) became a public health slogan.

>これは 秘密ひみつの 話はなしです。
This is a secret conversation.

密室みっしつで 事件じけんが 起おきた。
The incident happened in a sealed room.

“みつ” is the standard reading in compounds. For example, “ひみつ” (secret) and “みっしつ” (closed room) both emphasize the idea of something hidden or enclosed.