What are the requirements to unlocking Niji?

Any chance for Steam leaderboard support? This feature is always a big plus for me with shmups, since it keeps me coming back to try and beat my friends' scores.

There should be key remapping and you should be able to hold the laser button without releasing the rapid fire button. A higher difficulty setting would be nice too; I almost 1CC'd my first game.

After enjoying the game (on first day) and unlocked the secret ship on my own, the Power of Light achievement doesn't pop up (broken despite having the requirements met). Also, there is a full screen bug related to Windows 10. Whenever...

Is there any place I can buy/download the OST?