official letter; personal message (from a high official)
Refers to a formal letter or message sent by a high-ranking official such as the Emperor, Prime Minister, or a head of state. Often used in diplomatic or governmental contexts.
首相は大統領に親書を送った。
The Prime Minister sent an official letter to the President.
The ambassador handed the president a personal letter from his head of state.
天皇陛下の親書が大使に手渡された。
The Emperor's personal message was handed to the ambassador.
handwritten letter; autograph letter
Emphasizes that the letter is written by hand, often by the sender personally. Can be used for personal correspondence, but still carries a somewhat formal tone.
彼は直筆の親書を私に送ってくれた。
He sent me a handwritten letter in his own hand.
The prime minister entrusted the special envoy with a personal letter to deliver.
The king sent a personal letter to the leader of the neighboring country.
The foreign minister received personal letters from various countries.
書簡 is a formal literary term for correspondence in general, whereas 親書 stresses that the letter comes personally from (or is handwritten by) someone of high status.
書状 is an old-fashioned formal word for a written letter or document, while 親書 adds the specific nuance of personal or official authorship by a dignitary.
新書 (also read しんしょ) refers to a compact paperback book format, a completely different word from 親書, which means an official or personally written letter.
expert; connoisseur; person in the know · counter for messages and documents · worldly understanding; tact; insight · supernatural powers; magical powers
Composed of 親 (しん, 'parent; intimate; personally') and 書 (しょ, 'writing; document'). The combination suggests a document written personally or by someone in a close, authoritative relationship.