#   Kanji   Additional Kanji for JLPT  
  偶然 ぐうぜん guuzen (by) chance, unexpectedly, suddenly 2334
           
  偶に たまに tamani occasionally  
4459 偶々 たまたま tamatama casually, unexpectedly, accidentally, by chance 2334 2570
たまたま彼が居合わした
Tamatama kare ga iawashita
(By chance) he happened to be there