いらっしゃる
いらっしゃる · irassharu · JLPT N4 · verb-godan
-- honorific expression for いく
🙇 Shop greeting irasshaimase = this verb: honored one, come / go / be
You already know it from いらっしゃいませ, the welcome shouted in shops, which is this verb's polite command form. One respectful word replaces three plain ones: いく (go), くる (come), いる (be). Use it for others' actions, never your own.