いらっしゃる

いらっしゃる is a cornerstone of honorific Japanese. It is strictly a 尊敬語（そんけいご） (respectful) verb, meaning you use it to elevate the status of the person you are talking about. Never use it for your own actions.

1. Three Main Meanings & Disambiguation:
Because it covers three verbs, you must rely primarily on context to distinguish the meaning, though particles can provide helpful clues. For example, 東京にいらっしゃいますか（とうきょうにいらっしゃいますか） could mean "Are you in Tokyo?", "Are you going to Tokyo?", or "Are you coming to Tokyo?" depending on the situation. To avoid ambiguity, especially in business contexts, native speakers frequently use alternative honorifics like お越しになる（おこしになる） specifically for "to come".

• To be/exist: Replaces いる. Note that this only applies to people. For inanimate objects, polite forms like ございます or ある-based honorifics like おありになる are used. Often used with the particle に for location.
• To go: Replaces 行く（いく）. Often used with へ or に for direction.
• To come: Replaces 来る（くる）. Often used with から (from) or in contexts where the person has arrived.

2. The In-group/Out-group Rule:
In Japanese honorifics, you use いらっしゃる for superiors. However, the rule dictates that when you are speaking to someone outside your own "circle" (like a client) about an in-group superior (like your boss), you must drop the honorifics and use humble forms like おる or 参る. You can and should use いらっしゃる for your boss when speaking to other in-group members.

3. Honorific Copula（でいらっしゃる）:
When combined with the particle で, it forms the honorific copula (while functionally serving as the honorific for です or だ). For example, 先生です（せんせいです） becomes 先生でいらっしゃいます（せんせいでいらっしゃいます）。

4. Auxiliary Usage:
When attached to the て form of another verb, it replaces ている to describe a superior's ongoing action OR a state of being/result of an action (e.g., 読んでいらっしゃる（よんでいらっしゃる）, 知っていらっしゃる（しっていらっしゃる）, 結婚していらっしゃる（けっこんしていらっしゃる）). In everyday spoken Japanese, 〜ていらっしゃる is very frequently contracted to 〜てらっしゃる (e.g., 知ってらっしゃる（しってらっしゃる）).

5. Conjugation Rules & Real-World Usage:
This verb belongs to a specific group of five special honorific verbs (along with おっしゃる, なさる, くださる, ござる) that share the irregular 〜います ending:

• Irregular: The ます form becomes いらっしゃいます (not いらっしゃります). The polite imperative is いらっしゃい, which you will recognize from the common shop greeting いらっしゃいませ!
• Regular: All other forms follow standard 五段（ごだん） (Group 1) conjugation: いらっしゃらない (negative), いらっしゃった (past), いらっしゃって (て form - be careful not to say いらっしゃいて!), いらっしゃれば (conditional).
• Spoken Short Forms: In spoken Japanese, the て-form and た-form are frequently shortened to いらして and いらした.