Anti-Buubuuman strategy

If you're familiar with this encounter on higher difficulties, you'll know that this boss's bullet speed and rate increase significantly, making the encounter seemingly impossible to overcome... unless you know what you're doing!

Buubuuman's bullet speed and rate are similar to Loop 3 on Normal; you MUST have the Fire Bomb + Turbo Engine to beat him. One death and you won't have access to the Fire Bomb via the shop on your next life, so it's basically game over.

I've watched other strategies on Nico Nico that utilise the Smart Bomb, but these seem less reliable. Here, I always draw him to the foot of the screen (right or left side) when he charges, then immediately move to the top of the screen before he splits apart.

Depending on his positioning after he resets (he'll either be positioned closer to the left or closer to the right of the screen), manoeuvre to the opposite side to create distance and enough real estate to tap-dodge into while I charge the Fire Bomb.

The Fire Bomb takes approximately three seconds to charge, so about half a second before he splits, drop the bomb. However, you must ensure you are facing into the screen and towards the boss. If you drop it off-screen, it will not be visible, meaning it will fail to hit any section of Buubuuman, resulting in death (you'll be overwhelmed by a tidal wave of bullets that will be impossible to escape from).

Why is dropping the bomb so effective?

Only one section, or block, of the divided Buubuuman form actually takes damage (the block with a small version of his face). The game's RNG determines which block this is.

If it's at the top row, it's all good. Once you drop the Fire Bomb, you will inflict maximum damage, causing him to reform and start his attack cycle again, thus shutting down his deadly bullet attack.

If the RNG determines that it's a block on one of the lower rows, dropping the Fire Bomb will, at the very least, destroy all blocks in its path, reducing the number of bullets he fires in the process (each block fires bullets).

You can then drop another Fire Bomb, or as many as needed, to target the vulnerable block with his face.

As you'll see in the clip, if his face appears in the row at the very bottom and you've destroyed all the other blocks above, you will still need to tread carefully. The active blocks here will all still fire incredibly fast bullets, so you need to position yourself so you can just see the tops of the blocks before dropping the bomb, while staying out of view of the remaining blocks.

How to evade the bullet swarm

Once you drop the Fire Bomb and he starts firing, you need to act quickly.

As you should have positioned yourself near one side of the screen, slowly tap-dodge across to the other side while charging your bomb. This will give you enough space to escape his wave of bullets and, with the charged Fire Bomb, a means of hitting back to destroy blocks if the first bomb failed to take out the primary target (the main block with his face).

The tap-dodge is key here because you cannot change direction and need enough real estate and time to fully charge a second bomb.

Have a look at the video for the complete strategy. It took me a while to nail this down, but once you get to grips with it, it becomes second nature.