Turning a shoot 'em up into a hack and slash. A very fun challenge, it's a bit hard, but nothing too bad.
To use sword effectively, you must dash+attack in this very specific rhythm to deal optimal damage and abuse i-frames from hitting the enemy, this is harder than it looks. It is very easy to accidentally do a normal attack rather than a dash attack which keeps you wide open to take damage while also dealing less damage, it's also pretty tough to actually stay on the enemy when dashing left and right in a rhythmic manner.
By far the hardest parts of the run are the stage 1 and 2 bosses. Saki and Iru are fights where you really want to rely on a good shot like Beam Bazooka to deal big damage from afar. I can usually No-Damage stage 1, but I really didn't feel like resetting over the poor play in this run so I just kept going.