An Input Method Editor (IME) is software that enables users to type characters from writing systems that have more characters than can fit on a keyboard. For Japanese, the IME converts phonetic input (romaji or kana) into kanji-kana mixed text.

Japanese IMEs offer two input modes: romaji input and kana input. The workflow involves typing readings, viewing conversion candidates, and confirming selections. Predictive input and cloud dictionaries continue to improve efficiency. Japanese input method guides teach techniques for faster typing.

Major Japanese IMEs include Microsoft IME on Windows, the built-in Japanese input on macOS, and Google Japanese Input. Each has unique dictionary accuracy and conversion algorithms.

In web development, handling IME composition events is crucial. Properly managing compositionstart and compositionend events prevents issues like duplicate character insertion during conversion. Web app internationalization books cover IME handling patterns.