To the Cures' horror, Neo King Byogen uses his power to infect all of Sukoyaka City at once with the resulting infection also gradually spreading worldwide. Determined to restore the city by purifying the king, the Cures attempt to engage Neo King Byogen but discover he is protected by a barrier; he also effortlessly defeats them, causing them to lose their transformations. However, Queen Teatine arrives in time to help the Cures; using her powers along with her Healing Animal friends, she creates a barrier to contain Neo King Byogen and stop his infection temporarily, allowing the girls time to figure out how to defeat him. However, they are forced to flee when Shindoine attacks them, with Asumi using her wind powers to transport them outside Teatine's barrier. During their moment of respite, Asumi reveals she may have a way to counter Neo King Byogen's barrier: by using the Byogens' power along with their own, they should be able to pass through it. However in order to do so, Asumi must take in a Mega Part so she can use Byogen power. Despite initial protests, everyone agrees after seeing Asumi's resolve. Shindoine appears once again and the girls transform to fight her, hoping to get her remaining Mega Part, however Shindoine uses it to become stronger. After an arduous battle, the Cures manage to defeat Shindoine using Final Healin' Good Shower, restoring her to her original form, but Rate manages to tell them to use Healing Oasis to purify Shindoine further and allow Cure Earth to absorb her Byogen particle. Now with the ability to combat Neo King Byogen, the Cures prepare to face him.

Rabirin, Pegitan and Nyatoran reunite with their companions to take them to the Healing Garden for a visit. There, the three girls meet Asumi, Latte and Queen Teatine again; the queen thanks the girls for aiding them in protecting Earth against the Byogens. All three visitors befriend the other Garden residents, giving them some buns they brought along. However, they struggle to get along with a grumpy monkey resident who believes that humans are no better than the Byogens. As the four girls ponder over the monkey's words, a couple of MegaByogens spawn in, due to a wild NanoByogen which hid in the bun containers infecting the girls' buns. The girls transform to engage the MegaByogens but the monsters prove to be tough enemies with perfect cooperation among themselves. As the four Cures struggle to fight back, Rate summons a new Cure, Cure Summer, to the battle. With assistance from that new heroine, the four Cures manage to finally defeat the MegaByogen pack and purify the Fruit Spirit trapped in them. Afterwards, the three humans apologise for their carelessness but Queen Teatine assuages them, while Asumi reassures the monkey that humans can still fix the damages done to Earth. After leaving the Healing Garden, Nodoka, Chiyu and Hinata resolve to continue healing the world for their lifetime.