The 2000 miniseries FLCL (usually pronounced “Fooly Cooly”) has always been an outlier among popular anime in the US. While it includes familiar elements like fighting robots, malevolent corporations, and space pirates, they aren’t the focus. Instead, they’re more like set dressing for its hyperkinetic, experimental narrative about a young boy coming of age in a small town. FLCL has aliens, but it isn’t about aliens. It’s about the sensations of growing up and feeling stuck somewhere you don’t want to be — or as someone you don’t want want to be anymore.

Despite the wild, experimental nature of the series, American anime fans thoroughly embraced FLCL since its debut on Adult Swim in 2003, turning it into a cult hit with influences on familiar shows like Teen Titans and Avatar: The Last Airbender. Its legacy is so enduring that 15 years after the miniseries premiered on their channel, Adult Swim has funded two additional seasons: FLCL Progressive, the first episode of which airs tonight, and FLCL Alternative; which debuts in September.

The original FLCL follows Naota Nandaba, a pre-teen who lives with his widowed, self-absorbed dad and grandpa in a dead-end town. One day, Haruko Haruhara — the pink-haired woman who appears on most FLCL art and promotional material — crashes into Naota with her scooter, then clocks him in the head with a bass guitar. From there, Naota’s forehead serves as an unfortunate portal for the big, awful robots created by the unscrupulous corporation Medical Mechanica, which owns a hilltop factory in the shape of an iron. The soundtrack draws heavily from the discography of Japanese indie band The Pillows, whose wistful brand of alt-rock underscores every climactic scene.

The two new FLCL series shift the focus to new protagonists: Progressive follows 14-year-old Hidomi and her friend Ide as they encounter extraterrestrial beings who want to “unlock their hidden potential,” while Alternative introduces the 17-year-old Kana, whose humdrum life is interrupted by a giant mecha falling from the sky. It’s not entirely starting from scratch, however; the press release teases the appearance of familiar names like Haruko Haruhara and Atomsk, as well as the iconic Vespa Scooter from the original series.

While many of these touchstones are useful to know about in advance of the new seasons, why people care so deeply about FLCL is tougher to pin down. It’s not exactly accessible, on first glance. FLCL arrives with the force of Haruko’s instrumental assault, determined to shove you full of as much flashy animation, meta comedy, and legitimate melancholy as you can take for 20ish minutes. Each of FLCL’s six episodes are so packed with details, rapid-fire jokes and animation shifts that the show practically demands repeat viewings to disentangle the story from the noise. This is not a long-running series you can count on to gingerly guide you through a winding plot; each of its six episodes feels like a super-charged event where the story ends just as it starts to make sense.

Each of its six episodes feels like a super-charged event where the story ends just as it starts to make sense

But despite its eccentric and sometimes bizarre presentation, FLCL evokes the growing pains and complicated feelings of puberty (as well as unambiguous phallic imagery) in far more relatable terms. While some of its individual elements don’t always “make sense” (like why people swing guitars around like the jokey Hanna-Barbera vigilante El Kabong remains one of many open questions), the series as a whole coalesces into an abstract but sympathetic story about what it means to grow up — and one whose inscrutability demands closer attention.

FLCL’s protagonist, Naota, is one of those kids who’s convinced that being a grown-up is about acting cool, which means not caring about anything. Adulthood, for him, is defined by affected apathy and (eventually) the size of your eyebrows. He is especially irked by his father, his grandfather, and anyone else he perceives as needing to “grow up.” His only role model, his older brother, is gone, recruited to play baseball in America.

But while Naota may appear collected and cynical-beyond-his-years, he’s listless. He spends his days down by the river, hanging out with his brother’s delinquent ex-girlfriend and lugging around a baseball bat he’s never swung. He’s going nowhere, projecting his understanding of adulthood in no particular direction, and he holds the town responsible: “Nothing amazing ever happens here,” he says, even after robots start crawling out of his head. He feels trapped in a place where he doesn’t want to be, even if he doesn’t know where — or who — he wants to be yet. His passive discontent is conveyed through half-colored, half-finished backgrounds and the lazy yellow hue of the color palette, which evokes the drained feeling of being out in the sun too long.

The show settles into these quiet moments of powerlessness, which are enhanced by the incredible chaos elsewhere — impossible, frenetic action and outlandish, cartoonish distortions of character design and movement. This is how FLCL captures viewers’ imagination: not through anything specific or easily discernible, but through the broad strokes of oscillating tones and imagery. Loud, quiet, disturbing? It’s all a messy part of puberty.

Some of the series’ images are powerful, sad, and beautiful all at once, like the introvert truism “never knows best” scrawled onto the side of a lit cigarette being smoked at night on the bridge, alone. A girl watches a robot climb the ruins of a burnt-out schoolhouse and sees it gingerly take flight, as the sun peeks from behind the clouds and the ambling guitar strum of The Pillows gives way to their angsty vocal howl.

FLCL speaks to people because it embodies the profound loneliness of becoming an adult

FLCL speaks to people because it embodies the profound loneliness of becoming an adult. It’s a universal feeling, both in how it resonates with the audience and in how many of the characters share Naota’s aimlessness, but are too insecure to confide in one another as their perceptions of the world undergo wild shifts. And the show validates that loneliness, to a point; it suggests the affected adulthood of Naota and others is juvenile, but it that there’s no specific road map to adulthood and you pretty much have to come to terms with it on your own by getting out of your own head. FLCL empathizes but doesn’t purport to have the answers, because really, who does?

FLCL also fits in well with Adult Swim’s general surrealist aesthetic, which brings us to the question of these further seasons. Although the announcement of the two new series sparked questions from fans about whether there needs to be more FLCL, this scrutiny would be better served asking whether there can be more FLCL — a show whose bizarre confluence of references, emotions and non-sequiturs feels difficult, if not impossible, to replicate.

But after watching the first episode of Progressive, which Adult Swim aired in Japanese for April Fool’s Day, the answer seems promising: that instead of than trying to replicate the original, that the new seasons of FLCL are more interested in evolving. Shifting its focus to new protagonists has the potential to offer fresh perspectives, and while still under the supervision of the original’s director Kazuya Tsurumaki, FLCL Progressive and FLCL Alternative employ a different creative staff as well.

If the original series is about how there’s no single, prescribed way to grow up, then it follows that more episodes could succeed by focusing on others outside Naota and the people he knows, by creating different visions of youth than the one conceived by Tsurumaki and the people he worked with. As one of the show’s more obvious metaphors goes, sometimes to find out what happens, you just need to swing the bat.

Adult Swim’s website has the original FLCL series posted online in English, Hulu has it in subtitled Japanese, and Funimation has both.