ow, I know that the L-word is not an exact science.

But I also know that – with the right knowledge and a little practice – science can get pretty darn close.

Studies have shown that it takes between ninety seconds and four minutes to decide if you’re interested romantically in another person, and those physical symptoms can be monitored carefully.

Dilated pupils. Flushed cheeks.

Hair twiddling and wrist-exposing; mirroring the same body gestures. Too much eye contact or too little eye contact; laughing too much, listening hard and leaning towards the other person.

Unfortunately, it’s a language so complicated – so nuanced and subtle – that scientists have found that there’s only a 28% chance of accurately detecting flirtation, even if you’re the person being flirted with.

So it’s lucky I know what I’m looking for and have a naturally data-collecting kind of mind.

“Also,” Rin continues once we’re seated comfortably in the cafe. She’s nervously holding out a big bunch of large, bright key rings and going through them, one by one. “This is Rilakkuma. Kuma mean bear in Japanese, so he is Relaxy Bear. He likes eating odango.”

“Ah,” Jasper nods. “And this one?”

“This is Anpanman. ‘Pan’ is bread, ‘An’ is bean. He is Bread-Bean man, and he is always saving the world with eating of his head.”

Jasper blinks a few times. “Come again?”

“The world is eating his head.” Rin frowns with concentration. “Am I saying it wrong?”

“People eat this man’s head?”

“Hai.”

“He’s alive and made of bread and gives people chunks of his own head to eat?”

“Hai. And he fly with cape.”

I carefully watch Jasper deal with this information, waiting for the inevitable “Who the hell came up with this nonsense?”

“Ah,” he says eventually, nodding with patient understanding. “Gotcha.”

Oh my God. I knew it.

It’s like watching a destabilised Superman: I think Rin might be Jasper’s kryptonite.

In the meantime, Rin’s body language could not be easier to read. She’s still shy and anxious, but her blue skirts have been spread across the velvet armchair like something from Gone With the Wind, her cheeks are getting pinker by the second and her eyes are starting to darken and sparkle.

We are definitely on the right track.

Although maybe I should distract her from the presentation of tiny toys. We all get super nervous around people we like, but I’m not sure that this is the most efficient way to attract boys.

“Rin,” I say, clearing my throat, “why don’t you … uh … tell everyone about your experiences as a beautiful top model in Tokyo?”

That’s a little bit more universal, isn’t it?

“I’d imagine they can’t possibly be as – how should we put it? – colourful as yours, Harriet,” Jasper says, standing up and running a hand through his hair.

Bat poop. She told him.

Rin starts laughing. “Blue! So blue all over! Harry-chan is so funny.”

“Funny’s one word for it.” Jasper ties the stripy apron around his middle and raises his dark eyebrows. “I can think of a few others.”

I scowl. “If there’s a problem with your vocabulary, King, I can lend you my thesaurus.”

“Please do. I’m sure it will just blue me away.” He picks up a plate from the other table. “Now if you’ll excuse me, there’s something I’ve promised to do.”

He smiles at Rin.

Then he strides off behind the counter, grabs a damp cloth and turns on the noisy cappuccino machine.

“Blue …” Rin says experimentally. “Blue me …” Then her eyes widen. “I understand that English joke, Harry-chan! Blue and blow are similarity words!”

Her shoulders have relaxed, her smile is lighter and the sweet sparkliness I love so much about Rin seems to be slowly coming back.

I think this is actually working. I am a genius at making my friends happy, if I do say so myself.

“Rin?” Toby says, leaning forward and pointing at a little green key ring. “Is this Mameshiba? Body of edamame bean, face of shiba dog?”

“You know him?” Rin glows a bit harder. “He is most kawaii of all and know many interesting fact.”

“Oh I’ve seen the adverts,” Toby nods. “Chilli Bean Mameshiba tells us that cows produce a hundred litres of saliva a day.”

“Hai. And Jelly Bean Mameshiba say a koala’s appendix is two metre long.”

“Chickpea Mameshiba informs us that catfish have tastebuds all over their bodies.” Toby thinks about this for a few seconds. “That would be awful. Imagine if you stood in dog poo. You’d basically be tasting dog poo with your feet.”

“Itadakimasu,” Rin says with a little bow.

They both start inexplicably chortling.

“It means bon appetit in Japanese,” Toby explains to the room in general. “Hilarious.”

Nat looks up from her magazine and makes her eyes into circles at me. I widen mine back: our silent communication as seamless as always.

She’s right: this is going so well. Rin’s almost back to her normal self and I haven’t even started on my big plan for tomorrow yet.

“Here you go,” Jasper says, returning to the table with a tray full of drinks and plopping them down in front of us. “My one discernible skill, as promised.”

On top of each drink is a delicate picture sprinkled with cocoa in the foam: a robot, a high-heeled shoe, and a three-dimensional bear, made from foam rising out of the cup in a dome shape, with little ears sticking from the top.

They’re incredibly beautiful, and I have never seen anything like it before. How long has Jasper been able to do this? Why has he never done it before?

Oh.

“Su-goi!” Rin cries happily, clapping and picking up her teddy hot chocolate. “Oh I love him, Jasper! You are so kind! Thank you!”

“Woah,” Toby says, grabbing his robot. “Epic.”

“So cool.” Nat picks up her shoe.

I stare at the single remaining cup.

You have got to be kidding me.

Sketched in the Harriet-uccino foam in dark cocoa is a blob with eight arms, two eyes and a domed head.

There’s no doubt about it: it’s an octopus.

“Haha,” I say flatly. “Hilarious.”

“Sounds like it really was.” Jasper sits next to me. “Maybe you wanted to practise your seduction strategy with Charlie first, or were you just going in for a cuddle?”

I flush bright pink.

Yup: this is exactly why I didn’t tell him about Octo-gate. Or any of my other modelling experiences.

He finds my embarrassment way too amusing.

“Anyway –” change the subject before he asks about Paris – “guys, I have a favour to ask. My Vogue shoot is tomorrow, and I think I’m going to need a back-up model in case anything goes wrong. Rin, would you be able to come with me?”

Nat frowns. “I don’t think you get to pick your own …” I kick her under the table and glance pointedly at Rin then Jasper. “Oh. Got it. Err … bench-subbing yourself is totally standard procedure in the British fashion world.”

“Of course,” Rin says brightly. “I am happy to do it.”

Tick.

“I’ll come along t—” Nat begins before I give her another swift boot to the shins and a no, you will not expression, “—or I would, but … Vogue is so over right now.” Nat shrugs whilst going a little pink around the ears. “I mean, yawn. Boring. Whatevs.”

I literally have the best friend in the world.

“I’ve got quadruple physics,” Toby says, rubbing a dusting of cocoa off the end of his nose. “It’s actually my double physics lesson and then another one I go to that isn’t mine.”

“But …” Nat says, frowning, “aren’t you …”

“Such a shame,” I interrupt smoothly, then turn to Jasper. “Please can you come too? Tabitha’s going to need an extra pair of hands and she likes you.”

His eyebrows lift. “Really?”

“Well, she’s too young to know any better.”

“Touché.” Jasper throws a napkin at me. “I’ve got a class first thing but I can try and make it afterwards. Can’t miss seeing you in action, can I?”

Tick.

Delighted, I grin and resist the urge to rub my hands together and burst into loud Mad Genius laughter.

Everything’s lining up, just as I hoped.

A few more strategic but subtle nudges here and there and I think my job is done.

“Gah,” Nat says, glancing at her watch, grabbing her handbag and standing up. “I’m late for a night class again. Have fun tomorrow, OK guys?”

Then she gives me eloquent Best Friend eyes.

Harriet, they say, what exactly are you planning on doing?

I grin at her triumphantly.

Oh, nothing, I wink back. Just a little bit of chemistry.