Then he would set the dead wasp in a different place. Schemes can get silly when you have the power to see the future. All he'd need to do is arrange it so a premonitory corpse appears for Satsuki dying of anaphylactic shock to guarantee this works. Then take some action to save her so he's not a total hypocrite (just mostly a hypocrite).
This same guy re-arranged drinks in a store until he abused a 0.22675736961451% chance to kill Miho. Or stacked pencils on a staircase until it randomly killed his teacher. It's his serial killer modus operandi.
We are not even scratching the tip of the iceberg on just how broken this ability actually is.
Plan to kill someone and write information onto their body. This allows you to transmit arbitrary information into the past.
As for the limitation of only being able to see 1 day into the future: that applies to your past and future as well. If I plan to kill a person in 2 days, but do it 1 day earlier if I see the corpse tomorrow, the corpse will already appear today. Meaning you can recursively reach arbitrarily far into the future.