その時はシャワーを浴びていた。

that (something or someone distant from the speaker, close to the listener; actions of the listener, or ideas expressed or understood by the listener); the; um...; er...; uh...

time; hour; moment; occasion; case; chance; opportunity; season; the times; the age; the day; tense

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

shower

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to dash over oneself (e.g. water); to take (e.g. shower); to bask in (e.g. the sun); to bathe in; to be flooded with (e.g. light); to be covered in; to suffer (e.g. an attack); to draw (e.g. criticism, attention, praise); to have heaped upon; to be showered with