さえ details
Examples
even N — names an extreme or marginal case to imply weaker cases hold too
そんなの、子供さえ分かるよ。
sonna no, kodomo sae wakaru yo.
Even a kid gets that. casual
忙しくて、お昼ご飯を食べる時間さえありませんでした。
isogashikute, ohirugohan o taberu jikan sae arimasen deshita.
I was so busy I didn't even have time to eat lunch. neutral
当時は電気さえ通っていない地域がございました。
touji wa denki sae tootte inai chiiki ga gozaimashita.
At the time, there were areas that didn't even have electricity. formal
Formation
{N}さえattaches to noun
Notes
along — a bare positive assertion with さえ and nothing else tends to
read like the sentence trails off unfinished.
Related patterns
Similar
さえ states a bare fact about a single extreme case (子供さえ分かる); さえ〜ば takes that same extreme-case logic and turns it into a minimal sufficient condition for a result — 子供さえ分かればいい says a child's understanding alone is enough.
Lookalikes
Both often sit directly in front of a negative predicate (時間さえない／時間しかない), giving them an identical N＋particle＋ない shape, but they point in opposite directions — さえ names an extreme case to argue every lesser case fails too, while しか flatly states a shortfall with no scale implied.