TAKOBOTO

"thought so, but" OR, "would have thought so/imagined, but didn't"
I thought this restaurant would be cheap but (surprisingly) the bill was over 5,000 yen.
想像したろうか、いや、しなかった。思ったろうか、いや、思わなかった。

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ひるまだからぜったいこんでいるとおもいきや、いちにんもいなかった。

Despite having thought that it must be crowded since it was afternoon, (surprisingly) not a single person was there

このレストランはやすいとおもいきや、かいけいはせんえんいじょうだった！

I thought this restaurant would be cheap but (surprisingly) the bill was over 5,000 yen!

ゆきぐにでそだったかれのことだから、さぞかしスキーがうまいだろうとおもいきや、すべってはころび、すべってはころびのくりかえしだった

For someone brought up in a snowy country, you'd think he'd be great at skiing, but he just slips and falls, slips and falls.

ろうごはたいしょくきんのたくわえであんたいだとおもいきや、インフレでよきんがめべりしてしまった。

In my remaining years I thought I could live in peace and security from the stores of my retirement savings, but to my surprise , inflation has diminished the value of my savings.

チームのしょうりでしあいしゅうりょうかとおもいきや、さいごにだいぎゃくてんがおこった。

I thought that maybe the tournament would end with a win for team A, but surprisingly, it ended in a huge turn in the opposite direction.

This is a grammar I learned out of a book and was surprised to actually hear it used in real life on a number of occasions. You use this grammar when you think one thing, but much to your astonishment, things actually turn out to be very different. You use it in the same way as you would express any thoughts, by using the quotation 「と」 and 「思う」. The only difference is that you use 「思いきや」 instead of 「思う」. There is no tense in 「思いきや」, or rather, since the results have already went against your expectations, the original thought is implicitely understood to be past tense. (from Taekim)

Sasato

Ref # Kanzen Master Level 1 - p25 - no.28

LR

き is a particle indicating past tense, and や is a particle meaning "but" "however" etc. This is a leftover from older Japanese, since both are no longer commonly used in modern Japanese except in this particular phrase.

Tosiaki