thought…but
when…thought that…but
despite having thought…
Structure
- Verb + (か) + と思いきや + Phrase[past]
- い-Adj + (か) + と思いきや + Phrase[past]
- な-Adj + (だ) / (か) + と思いきや + Phrase[past]
- Noun + (だ) / (か) + と思いきや + Phrase[past]
[Noun/な-Adj + だか思いきや is generally not used. Either か or だ (or neither) is used
[Aと思いきやB is used to emphasize the speaker’s surprise that contrary to expected result A, B is actually the case]