Complex sentence: Andou asks Mai if she'll be there with him when he dies, but Mai tells him she's too scared, he understands and decides to try to find out more about the virus that killed Takayama and his son.
Split into simpler sentences: Andou asks Mai if she'll be there with him when he dies, but Mai tells him she's too scared. He understands and decides to try to find out more about the virus that killed Takayama and his son.