Daily 800k+ mission is easy even for F2P because they don't have weird gimmick and you can stuff 3 best girls in one team and the 4th can be weak because helper will cover it anyway. Kodaibana is much harder without helper team and you need to distribute firepower evenly between 4 teams. (some more than others if they will face boss)

Anyway congratz, you will get some rainbow skillbloom this way too.