It's pretty simple when it gets down to it but is really confusing. so on the second floor of magatsu inaba (which doesn't have named floors as there are only 2) you must reach the door leading to adachi but it's forced shut by a power so you must jump down the hole just before the door which takes you to magatus mandala (which has named floors called worlds) just move on through like normal but world 3 has a gimmick which makes it so you can't encounter shadows or you get kicked out and must go back to world 1. once you do that beat the mini boss on world 6 use a goho-m get back to floor 2 on magatsu inaba and beat the ♥♥♥♥ out of adachi. just a word of advice make sure your max health before the boss as you can't use a goho-m to get out once you are there.