それは君の責任だ。

that (indicating an item or person near the listener, the action of the listener, or something on their mind); it; that time; then; there (indicating a place near the listener); you

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

you; buddy; pal; monarch; ruler; sovereign; (one's) master

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

duty; responsibility (incl. supervision of staff); liability; onus

be; is; indicates past or completed action; indicates light imperative