私は、かぶっていた帽子で彼女だとわかった。

I; me; private affairs; personal matter; secrecy; selfishness

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

to put on (one's head); to wear; to have on; to pull over (one's head); to crown (oneself); to be covered with (dust, snow, etc.); to pour (water, etc.) on oneself; to dash on oneself; to ship water; to bear (e.g. someone's debts, faults, etc.); to take (blame); to assume (responsibility); to shoulder (burden); to overlap (e.g. sound or color); to be similar; to be redundant; to be fogged (due to overexposure, etc.); to close; to come to an end; to get a full house; to sell out; to blunder; to bungle; to fail; to be deceived

hat; cap

indicates location of action; at; in; indicates time of action; indicates means of action; cause of effect; by; and then; so; indicates continuing action; indicates certainty, emphasis, etc.

she; her; her; girlfriend; sweetheart

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

if; when; and; with; particle used for quoting (with speech, thoughts, etc.); quoting particle; promoted pawn; indicates question (sentence end)

to understand; to comprehend; to grasp; to see; to get; to follow; to become clear; to be known; to be discovered; to be realized; to be realised; to be found out