drafter; author of a draft; original author
Refers to the person who originally drafted a document, proposal, or plan. Common in business, legal, and administrative contexts.
The drafter of this proposal is Mr. Tanaka.
The signature of the original author is required.
作成者 is a general term for 'creator' or 'maker' of any document or item, without the specific nuance of drafting a proposal or plan.
Compound of 起案 (drafting, making a plan) and 者 (person). The exact historical derivation is uncertain, but the word follows a common Sino-Japanese pattern for occupational or role nouns.