Two of the country’s best coffeehouse chains go head to head in this battle of seasonal flavours.

Autumn has finally arrived in Japan, which means it’s the season for sweet potatoes. Here in Japan, they don’t just eat these delicious root vegetables, they drink them too, and at the moment you can slurp them up at two rival American-born coffeehouse chains, Starbucks and Tully’s Coffee.

The seasonal drink at Starbucks is called the “Yaki-imo Kobashi Caramel Frappuccino” (“Aromatic Baked Sweet Potato Frappuccino“), and although it officially goes on sale on 4 September, our reporter K. Masami was able to get an early taste of it, as Starbucks Rewards members like herself can purchase the drink in the two days leading up to the official release.

On the other hand, Tully’s Coffee has been selling an “Oimo Tea Shake” since 28 August, with the oimo (literally “potato”) referring to sweet potato. As an ardent lover of the autumnal vegetable, Masami was keen to try both these drinks to see which one is worth your yen, and find out if the more popular Starbucks chain does things better than Tully’s.

▼ She started the taste comparison at Starbucks, where the new Frappuccino cost her 700 yen (US$4.81).

This is a sweet potato lover’s dream, with pieces of sweet potato in the milky base, and in the form of imo kenpi (sugar-coated sweet potato chips) in the topping. When combined with the caramel sauce and vanilla flavour in the body of the beverage, this combination of ingredients is designed to mimic the taste of a canelé.

It’s a luxurious-looking drink, and when Masami asked the store clerk if they would recommend any type of customisation, they told her it tasted great with an oat milk substitution for an additional 55 yen, so she decided to give that a try.

Dipping her spoon into the mixture, she could see it had a thick, heavy texture, and when she took her first sip, the moreish mouthfeel made it incredibly satisfying. Drinking it through a straw delivered sweet potato chunks onto the tongue, where they danced with bitter caramel on the palate, creating a delicious taste and texture that she describes as “the flavour of happiness“.

It was a fantastic Frappuccino, and filling as well, making it worth every yen. So how would the Tully’s drink compare?

This is a very different drink, in that it contains black tea, and unlike the Starbucks Frappuccino, which is only available in a Tall size, it comes in two sizes: Short (690 yen) and Tall (750 yen). This makes it slightly more expensive than Starbucks, but with a sweet potato sauce and Earl Grey milk tea in the mix, it appears to contain pricier ingredients.

▼ The whipped cream topping is intertwined with sweet potato sauce, and sprinkled with black sesame seeds.

Staff recommend mixing the topping into the beverage so that’s what Masami did, and the first thing that surprised her when she sipped it was the beautiful aroma of Earl Grey. The tea flavour was quickly followed by the taste of sweet potato, creating a harmonious blend that was absolutely delicious.

Though she initially thought there’d be a clear winner after the tasting, it turns out that this was a call that was too close to make. On the one hand, you can enjoy an abundant taste of sweet potato in the Starbucks drink, while on the other hand, the Tully’s drink offers a flavoursome blend of sweet potatoes and tea, in just the right balance.

Both are delicious, but different, so Masami recommends trying each of them if you can, with Tully’s first as it’s slightly lighter in flavour. One thing they do have in common is their limited-edition availability, as the Frappuccino is only on the menu until 10 October, and the Tea Shake will be sold while stocks last, so you’ll want to get in quick to try them!

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