“Sigh / Lament / Moan / Grieve” in Japanese is 嘆, read tan, nage (たん, なげ). It is a Jōyō kanji taught in Japanese secondary school (junior & senior high) — the 高手 · Master tier beyond the grade 1–6 Kyōiku set, and appears in words such as 感嘆 (admiration).
What does 嘆 mean?
Same sound, different character — the classic trap. Compare them side by side: