One of the songs in the brand new rhythm game, Hatsune Miku: Project Diva X, is called Holy Lance Explosion Boy, and it's about an unsettlingly young boy accidentally getting someone pregnant, featuring lines like: "This 0.02mm barrier is seriously getting annoying." If the thought of a kawaii, virtual boy's condom splitting and his holy lance exploding is a little too much for you, then you're probably not part of the target demographic for the game.

Hatsune Miku is a virtual popstar from Japan who sings songs created with a vocaloid synthesizer, and she's making her PlayStation 4 debut with Project Diva X. She exists within the world of the game, and she knows that, telling you that she can't sing without your well timed button presses. The world she inhabits is made up of clouds – think differently themed hub worlds – that are tragically losing their mojo thanks to some disaster or other. The only way to recharge the power to these clouds and save Hatsune Miku's world is to sing incredibly upbeat pop songs and maybe, just maybe, learn a few important life lessons along the way.

The story, if you haven't already guessed, is absolute bobbins. Featuring cut-scenes that amount to little more than vignettes between Miku and her various acquaintances learning the power of friendship, how to be cute, and saving the day by believing in themselves, the fiction is almost satirical in how disposable it is. But while that may be a crippling issue for a lot of games, for Project Diva X it doesn't really matter, and may actually add to the charm of the title depending on how you feel about Hatsune Miku and her patented brand of cuteness.

Hatsune Miku herself is an extremely likeable protagonist. She's perennially upbeat and she always wants to help. She's got a cutesy anime style and long, turquoise pigtails that improbably never fall out of place. We suppose if you know that you're part of a virtual world then there's little point in adhering to our laws of physics or hair care. Her cast of friends, who also become playable a short while into the game, are equally sweet and colourful, and they're varied enough that you'll likely be able to find at least one that appeals to you.

Upon heading to the first cloud at the start of the game you'll be told that you need to recharge the voltage – that's the life force, if you will – of the cloud via the medium of song, and so Miku must grab her microphone and sing her little heart out to save her world. The song begins, and in order to complete the mission, you'll have to either tap face buttons, flick an analogue stick (or the touchpad), or occasionally tap a face and directional button at the same time when prompted by the on screen icons.

While that may not sound revolutionary for a rhythm game, where Project Diva X throws an interesting spanner into the works is in the haphazard nature of where the icon prompts appear on the screen. If you're used to playing lane-based rhythm games like Guitar Hero or Rock Band, then the way that Hatsune Miku works may throw you off guard at first. The button prompts in Project Diva X can appear anywhere on the screen at any time, and then an icon will travel across the screen to the prompt, and it's when the two meet that you have to input your command.

This may not sound inherently complicated, but when a dozen prompts are appearing all over the screen one after another, it takes a surprising amount of concentration to remember in which order the prompts appeared on the screen, and thus which order the button icons will travel to them in. Throwing slightly more difficult moves like pressing two buttons simultaneously into the mix just complicates matters further. It may surprise you just how quickly a perfect run can fall apart once you make one mistake and suddenly every button prompt flummoxes you.

The core gameplay of Project Diva X is incredibly well designed. As far as rhythm games go, the mechanics are practically flawless. Playing on Easy will mean that you'll only ever need to use one face button and an analogue stick, while moving up to normal will add another face button to the mix, and the occasional inputs that require two button presses at the same time. Going up a level in difficulty also means that the number of inputs you're required to make is increased, which is a bit of a double edged sword: more button presses means that you've got more to do, but it also means that you can amass a higher score thanks to each correctly timed button press adding to your tally. Later you'll unlock higher difficulty modes which again makes the game more complicated, but allow you to rack up even higher scores, and potentially unlock more rewards.

Occasionally during a song you'll enter a mode called Chance Time in which every note you hit will slowly fill up a star-shaped meter in the bottom-left of the screen. If you fill it up within the time limit then you'll unlock a new module – that's a fancy name for a costume – and have a quick wardrobe change mid-song. Knowing that you can unlock something for getting a couple of dozen button presses right adds an extra level of pressure to the proceedings, and a successful Chance Time bid always feels like a victory. On a slightly sour note, the modules that you'll switch to in Chance Time appear to be random, and so sometimes you'll switch to one you already have and that can be a little disappointing. Also, at launch, there's modules that you can buy as DLC which are useful if you have the money, but aren't at all required to enjoy the game.

The different modules are more than just an aesthetic change. Each module has abilities tied to it, whether it will give you bonus points for getting fifty correct button presses in a row, or increase your chances of unlocking new items at the end of a completed song. The modules are also class based, and these classes are tied to the different clouds that you'll be working through in the story. There's Cute, Elegant, Quirky, Cool, and Classic. Having the right outfit is important as you'll get bonuses that will help you rack up points more quickly for looking the part. Remember to co-ordinate your accessories just like you would before a big night out – matching gold with gold, or cute bunny ears and a fluffy white tail may yield more bonuses than a mashup of different styles would.

You start the game in the Classic Cloud, which is a mix of fairly standard J-pop tunes. Once you've completed all of the songs in the cloud to a satisfactory standard you'll be able to take part in the Main Event, which is a medley of a handful of different songs, switching up time signatures and styles on the fly. These Main Events are a definitive highlight of the game as they're a blast to play, and will surely keep you on your toes.

Upon completing a cloud you can move on to a new one, each featuring songs in different styles that loosely fit into a theme. The songs themselves are largely catchy. While there's a few throwaway tracks, there's none that we found particularly grating, and there's some that are guaranteed to get your toes tapping, even if you hate yourself afterwards for doing so. Aside from the aforementioned Holy Lance Explosion Boy, other standouts include the superhero themed epic Urotander, Underhanded Rangers, and a song called Satisfaction that is only a smoke machine and the taste of Blue WKD away from being a bona fide club banger.

If there's one gripe with Hatsune Miku: Project Diva X it's that the game can be a bit of a grind. At the start of the game you'll only be able to play on easy or normal versions of the songs, and so you have to finish the whole game on normal to unlock the more satisfying challenge modes. Fortunately, finishing the songs required to unlock the further difficulty settings should only take about four hours, and unlocking costumes and accessories along the way will surely soften the blow, while getting you used to the mechanics of the game.

Aside from the main game, there's also a photo mode which lets you put the popstars into various poses and take pictures of them – make of that what you will – and a fairly robust video editor mode that lets you create your own music videos for the different songs. There's a little gifting mini-game too, in which giving the idols gifts will increase your friendship with them, but none of it is necessary to make progress in the game.

Conclusion

Hatsune Miku: Project Diva X is definitively the finest music game on PlayStation 4. It boasts a ton of replay value, and the mechanics are in a league of their own. Trying to better your own high scores can become incredibly addictive, and you could sink hours into the game without even realising it. If you know that you hate J-pop then this game won't be for you any more than a great football game like FIFA 15 would be for someone that hates sports. But if you're willing to take a chance on Hatsune Miku and her sugary sweet brand of pop, then you'll find an incredibly well-crafted rhythm game that is welcoming to new players while providing just enough of a challenge for veterans of the genre.