遂に
ついに · tsuini · JLPT N3 · adverb
finally
🏁 遂 = carry through to the end, so 遂に = having seen it through: at last
The kanji 遂 means to accomplish or carry out, as in 完遂 (kansui, full completion). Add に and you get by way of finishing, which became finally. Sound hook: tsu-i-ni, as in it's done and I'm in.