放(ほう)課(か)後(ご) houkagoは wa練(れん)習(しゅう) renshuuで de大(おお)忙(いそが)し() ooisogashiです desu。 I'm swamped with practice after school. Literal After-school [topic-は] practice [because-of-で] super-busy-[polite-です] 大忙し uses the prefix 大 to intensify 忙し (busy). The で here is causal: busy because of / on account of practice. Subject is omitted. gamesschoolsportsで (cause/reason)subject omission
放(ほう)課(か)後(ご) houkagoは wa練(れん)習(しゅう) renshuuで de大(おお)忙(いそが)し() ooisogashiです desu。 I'm swamped with practice after school. Literal After-school [topic-は] practice [because-of-で] super-busy-[polite-です] 大忙し uses the prefix 大 to intensify 忙し (busy). The で here is causal: busy because of / on account of practice. Subject is omitted. gamesschoolsportsで (cause/reason)subject omission