Bramble has always dreamed of becoming a great hero in order to gain recognition from everyone, especially his older brother, Briar. A piece of the alien nucleus that fell from the sky broke the peace of Pine Tree Mountain, but unexpectedly, Bramble merged with the alien nucleus and became a bear with alien wisdom and energy. However, this also brought about the pursuit of "alien" Abu who wanted to reclaim the nucleus.

Genetics have never been so hilarious. A thrilling new place opens on Pine Tree Mountain, "Wild Land", that offers a legendary experience. By wearing a gene-altering bracelet, guests can transform themselves into a variety of animals. Vick discovers that Wild life is hosting a competition with a massive grand prize and decides to enter. He teams up with Bramble and a mysterious man named Leon, astonishingly winning the tournament. Soon afterwards, Leon is caught trying to secretly copy the park data by the owner, Tom, and Vick discovers that hybrid guests are going feral and attacking others - Who is the mysterious Leon? Is Tom the mastermind Vick has to fight?

During their decade-long quest to defeat the Demon King, the members of the hero's party—Himmel himself, the priest Heiter, the dwarf warrior Eisen, and the elven mage Frieren—forge bonds through adventures and battles, creating unforgettable precious memories for most of them. However, the time that Frieren spends with her comrades is equivalent to merely a fraction of her life, which has lasted over a thousand years. When the party disbands after their victory, Frieren casually returns to her "usual" routine of collecting spells across the continent. Due to her different sense of time, she seemingly holds no strong feelings toward the experiences she went through. As the years pass, Frieren gradually realizes how her days in the hero's party truly impacted her. Witnessing the deaths of two of her former companions, Frieren begins to regret having taken their presence for granted; she vows to better understand humans and create real personal connections. Although the story of that once memorable journey has long ended, a new tale is about to begin.

The fourth season of FLCL, and sequel to FLCL Alternative. It centers on three teenagers who graduated and have started working. The CGI anime will have a theme of the feeling of being an adult.