さえ is a versatile particle that is used most commonly with the affirmative conditional to place emphasis on a minimum requirement (e.g., “If only I had time, I could travel the world”). In this case, さえ takes the place of the subject or object particle (が or を).
Minimum Requirement: If only… (さえ〜ば)
【Noun】さえ【Verb Conditional 〜ば】
You will very often see it used with the verb “to exist”: さえあれば.
ちょっとした機会さえあれば成功できると思う。
If I just had half a chance, I think I could make it work.
暇さえあればいろいろな計画が実現できるだろう。
If I only had time, I could realize so many plans.
お金さえあれば明日のことを心配せず毎日を自由に過ごせるだろう。
If I just had money, I could spend every day freely without worrying about tomorrow.
Extreme Example: Even (さえ)
さえ can also take the same role as でも or も when used without the conditional. The meaning is identical (“even”), but さえ places a stronger emphasis on extreme or unbelievable examples.
彼の電話番号って？現在どこに住んでいるかさえわからないよ。
His phone number? I don’t even know whereabouts he’s living now.
足が痛くて歩くことさえ無理です。
My foot hurts—even walking is impossible.
Verb Actions: If you just do… (さえすれば)
さえ can also be appended directly to verbs to mean “If you just do [Action], then [Result].” This structure is highly common in both daily conversation and writing, and is frequently tested on the JLPT N3.
【Verb: Stem】さえすれば
【Verb: te-form】さえいれば (or くれれば)
薬を飲みさえすれば、すぐ治ります。
If you just take this medicine, you will get better immediately.
そのポイントに合意してくれさえすれば他は合理的な妥協点を見つけられるかと思います。
If you could just agree to this point, then as for the rest I think we can find a reasonable compromise.