In My Hero Academia: World Heroes’ Mission, a mysterious terrorist group called the Humanize are introduced. They strongly believe in the "Quirk Singularity Doomsday Theory." The theory states that as future generations continue to be mixed with the Quirk genes, the power it holds will lead to humanity’s demise. Furthermore, Humanize believes that Quirks are a disease, and so, they plan to “cleanse the world” by exterminating anyone who has one. Humanize planted "Ideo Trigger Bombs" in various countries, and these explosives are said to make a Quirk-user lose control of their Quirk, leading to mass destruction. To save and protect everyone, Pro-Heroes from around the world, and the U.A. Academy heroes-in-training, unite to thwart the efforts of the mysterious group.

8-year-old Hiyori, who lost her parents, and Yui, seeking to escape her violent father, got off at a Kitsunezaki station one day. The great earthquake and tsunami had changed their destinies. Their lives were saved, but they were perplexed when asked about their identities at an evacuation site. It was an old woman named Kiwa Yamana who lent them a helping hand. From that day, Yurie was known as Yui, Moeka as Hiyori, and together with Kiwa, the three women began a wonderful communal life together at the old house "Mayoiga" overlooking the sea.

The story centers on Hiwa Natsunagi, a novice at hula dancing who nevertheless takes a job as a hula dancer at the real life Spa Resort Hawaiians hotel. The film shows the relationships between her and her colleagues.

One day, Nobita picks a small rocket from which a small-sized humanoid alien named Papi comes out. He comes to Earth from a planet name Pirika to escape its evil PCIA army. At first, Doraemon and his friends are confused by Papi's small size, but with the gadget "Small Light", they shrink and play together. However, the whale-shaped battleship which was chasing Papi comes to Earth and attacks them. Papi blames himself for having involved everyone but, tries to fight against the PCIA army. In order to protect Papi and his planet, Doraemon and his friends travel to Pirika.