noun
A formal document used in business, legal, or institutional contexts to confirm one's intentions or agreement.
契約前に意思確認書を提出してください。
Please submit a letter of intent before the contract.
念書 is a written pledge or memorandum, often less formal than a letter of intent and used for confirming promises or understandings.
Compound of 意思 (intention) + 確認 (confirmation) + 書 (document).