This depends on the number of grazes and enemy kills the player has managed to achieve in that particular chapter, and scoring more than 1 million points will either grant the player a life piece (Legacy mode only), of which three form an extra life, or a bomb piece (Pointdevice Mode only), of which three form an extra bomb.

In the distant past on the Moon, the Lunarian goddess Chang'e orders her husband Hou Yi to kill the son of her rival Junko.

In a grief-stricken fit of rage, Junko murders Hou Yi and becomes consumed in her anger, becoming a pure identity-less divine spirit in the process that lives solely to enact revenge on Chang'e.

Some time after the events of Imperishable Night, Junko invades the Moon with an army of fairies, with the help of her friend Hecatia Lapislazuli, the goddess of Hell, to search for Chang'e.

In the present day, the Lunarian fugitives Kaguya Houraisan and her servant and fellow goddess Eirin Yagokoro discuss the potential Lunarian invasion in their home of Eientei, and Eirin conjures a special medicine, the Ultramarine Orb Elixir, which temporarily removes the impurity of death and allows the user to experience the immediate future.

Eirin then asks Reisen Udongein Inaba, a fellow moon rabbit refugee who serves as the bodyguard of Eientei, to deliver the elixir to Reimu Hakurei, Marisa Kirisame, and Sanae Kochiya, also telling her to drink it for herself.

Meanwhile, a metallic spider-like rover from the Moon crashes into the Youkai Mountain and starts to roam around, purifying any land it passes by and leaving no signs of life.

While flying at the foot of the Youkai Mountain, the heroine encounters the frontline moon rabbit troops of the Eagle Ravi, a Lunarian Earth Recon Unit sent to purify the Earth, and encounters the low ranking infiltrator Seiran, who lets slip that their forward base is present at the mountain's lake.

Revealing that she can change the course of fate inversely with her words, her ability ensures the Lunar Capital Transfer Plan will not come to fruition as a result of her discussion.

The leader of the hell fairies, Clownpiece, who has been given an order by Hecatia not to show visitors from the Lunar Capital mercy, then attacks the heroine.

[b] After the hero defeats Junko, the invasion does not stop, and the residents of the fake Lunar Capital start to ponder if their reality is false.

[2] ZUN stated that he was inspired by games such as I Wanna Be The Guy, which feature extreme difficulty combined with the ability to freely retry each stage.