当事者 (とうじしゃ)person concerned; interested party; related party

当事者, its kanji, and other words that share them.Open this graph

Kanji in 当事者

当初とうしょbeginning; start
当局とうきょくauthorities; relevant authorities
当時とうじat that time; in those days
当選とうせんbeing elected
当面とうめんcurrent; urgent
担当たんとうbeing in charge (of an area of responsibility); being responsible (for a work role, etc.)
本当ほんとうtruth; reality
当然とうぜんnatural; right
事件じけんevent; affair
事務じむoffice work; clerical work
事務局じむきょくsecretariat; executive office
事務所じむしょoffice
事実じじつfact; truth
事情じじょうcircumstances; conditions
事態じたいsituation; (present) state of affairs
事故じこaccident; incident
容疑者ようぎしゃsuspect (person)
患者かんじゃpatient

See how 当事者 connects to the rest of Japanese.