I don't think Ango didn't help Hana cause he wanted to cover his crime (He later told Ryo he didn't want either Hana or Haru dead), I think he was confused (he thought he was being tested in the cave), and he thought "bad-meany-Hana" wanted to hurt poor-innocent-Ryo (Ango is really messed up XD)

Ango isn't the guy who covers up, he isn't Ryo!