Having read the first book of the Tokyo Alien Bros. manga, I confess I'm baffled, and not for the obvious reasons. The scenario isn't outlandishly way-out. Instead, it's very simple: two alien brothers living in modern Tokyo, posing as humans. Nor is the storytelling unclear; creator Keigo Shinzō presents his tale perfectly lucidly. And yet, by the end of the first book (of three), my initial interest had turned to boredom, and I couldn't see much of a point to what I'd read so far.

The titular alien brothers adopt the names Fuyunosuke and Natsutaro, and they're on Earth as part of a research mission for their people. In their natural form, they look like walking (but very unfrightening) blobs or slimes, and they can take on human forms in a trice. As the story opens, Fuyunosuke has been on Earth quite a while, and he's got the human thing down to a T. He's enrolled at university, looks like a wholesomely handsome youth, and pretty much everyone likes him. That even goes for his male classmates, who sigh in envy as he's surrounded by adoring girls.

Natsutaro, Fuyunosuke's brother, turns up in Tokyo in the first chapter. Looks aren't his problem – the form he takes is handsome enough. But he's completely new to human existence, and extremely accident-prone. Truck-kun wallops him twice in this volume, but does him no harm; salt, though, is another matter. He's completely baffled by all the human conventions that Fuyunosuke knows so readily, and spends much time either shadowing his sibling, or holing up online and posting his wisdom like the next John Titor.

Fuyunosuke also spends a lot of the book wandering around confusedly in a bathrobe. This suggests a nod to the British SF-comedy The Hitchhiker's Guide to the Galaxy, whose hapless hero Arthur Dent similarly wandered round in a dressing-gown. Hitchhiker's also had an alien living quietly incognito on Earth. And there's a funny scene where the brothers watch an Independence Day-style movie about a fiery alien invasion on TV, and talk about how stupidly inefficient that would be. Superior beings could rule the Earth entirely in secret, with humanity none the wiser. Any Hitchhiker's fan knows the mice did just that.

Not that Tokyo Alien Bros. feels much like Hitchhiker's. There's an, ahem, surprising scene very early in the book. Fuyunosuke is entirely aware he's a looker, and has learned to enjoy girls' company. He's meeting some college friends when he's distracted by a pretty girl on a riverbank, and promptly leaves his companions behind. Helped by his mind-reading, he entices the new girl to a love hotel, and… Well, what happens isn't horrible or criminal, but it's eew enough to become an instant meme if it was in an anime.

It's not obvious why Shinzo takes things there so fast, as nothing similar happens in the rest of the book. (Well, except for one passing gag with a dog which might give you nightmare flashbacks to John Waters' film Pink Flamingos.) In retrospect, that may be the joke; that from Fuyunosuke's perspective the love hotel scene is so innocuous that he's forgotten it by the next page, and more fool us for thinking it signals anything about the manga's upcoming content.

In which case, fair enough, although most other writers (including Hitchhiker's' Douglas Adams) would play off a human perspective against the alien one. In Tokyo Alien Bros., we do glimpse human reactions, such as the surprised girl's in the first chapter. However, they're treated as incidental. Of all the normal humans introduced in the book, there's no sign any of them will become significant characters, or even that we'll see them again. The most substantial human character appears at the book's end in a short bonus chapter; he's a misanthropic loner student who finds himself drawn to the annoyingly cheery Fuyunosuke. He could make an interesting foil to the aliens, but again there's no sign he'll return.

Insofar as the series seems to be shaping up as anything, it's as a riff on neurodivergence. Two chapters build up to punchlines (of sorts) that turn on the characters' inability to understand the deeper nuances of human thinking and emotion – even Fuyunosuke has limits. Consequently, humans get upset or enraged at what the brothers do, not that it causes the aliens more than mild surprise. In that way, the brothers are like umpteen anime characters – early Violet Evergarden, for instance – or like the android Data in Star Trek: The Next Generation, except they have no-one to tell them where they went wrong.

That might sound like a fair basis for a manga, and it clearly is for many readers. The manga inspired a live-action TV version in 2018, and was nominated for Best Comic at the Angoulême International Comics Festival in France. I can only say the thin payoffs of the individual chapters didn't seem worth the journeys. It's all just mildly funny-peculiar, and I was getting pretty bored by the time I finished the book.

At least I could appreciate the manga's sense of place, given I'm a frequent visitor to Tokyo. Much of the manga takes place in real locations; Shibuya's Scramble Junction is obvious, but there are journeys to the rowdy nighttime streets of Kabukicho, the great plant-filled pond at Ueno, and the venerable “Hanayashiki” amusement park in Asakusa. I loved the idea of a spaceship disguised as a kids' playset (“Man, it got all graffitied!"), allowing for a quick trip round the world from Ayers Rock to Sacré-Cœur. The human figures are unbeautiful, but they're good at conveying the kookiness of the title couple, and of the series' concept as a whole. If only the execution was more engaging.