even N (implying 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
Variants
さえもsaemoformal
stacks も onto さえ for extra emphatic force — leans written/formal, the same emphasis-register skew as そうにない／場合には／割には
でさえdesaecolloquial
inserts で before さえ when the noun needs its own copula link — more frequent than bare Nさえ in everyday speech, 子供でさえ分かるよ
さえ
さえsaeN3neutral