接続・逆接N1
〜としたことが
of all people/things... / to think that... (should have known better)
Structure
N + としたことが
Explanation
N + としたことが: the person normally wouldn't do this, but did; surprise or disappointment.
Examples
彼としたことが、大切な会議を忘れるなんて。
Fancy him forgetting an important meeting!
真面目な彼女としたことが、期限に遅れるとは。
To think that reliable her would miss the deadline!
Note
The person normally wouldn't do this, but did. The main clause often ends with とは for surprise.
Related Grammar
〜とは、〜なんて〜とは思わなかった