Verb (5-dan, る, intransitive)
1. to enter; to go into; to trespass (on)
僕には、まるで立ち入れない戦いだ。For me, it is a battle I cannot enter at all.
2. to meddle (in); to interfere (in); to pry (into)
いえ、立ち入ったことを聞いては駄目ですね。No, I shouldn't pry into personal matters.
3. to go deeply (into an issue); to delve deeper (into)
判断がつかないことには深く立ち入らない。I don't delve deeply into matters I can't make a judgment on.