Wags and kisses are all well and good when you want to know if your dog loves you but don’t help too much when you want to know how they’re really feeling. A Japanese biologist has taken this problem head-on with Inupathy, the “world’s first dog mental visualizer.”

The Inupathy band — “inu” means dog in Japanese — measures your furry friend’s heartbeat in order to get a sense of what emotion he or she is feeling. It accomplishes this by looking for Heart Rate Variation (HRV). The team behind Inupathy says that they have collected the HRV data for happy, focused, excited, and relaxed states, and are planning to add more as they go. When your four-legged friend is feeling one of these emotions, the harness’ embedded LEDs will glow a different color — red for excited, blue for relaxed, white for focused, and a rainbow effect for happy.

More Smart Pet Tech: Dog whisperer alert: this AKC affiliated smart collar helps you stay in touch

The harness can connect to a smartphone through Bluetooth LE, so when you’re in range of Fido, you can check in on his feelings. If he is feeling a little blue, you can launch the “Let’s Play” mode in the app, which will suggest games for you to play with your pet and show you the change in their mood as the game goes on. It will even rate how much fun your dog is having on a scale of 1-100, so you can add challenges or change the tempo to maximize the enjoyment.

Joji Yamaguchi, the biologist and man behind the Inupathy, plans to expand the capabilities of Inupathy into tracking your dog’s health as well, utilizing the heart rate tracking capability to do so.

Considering wearables may not be all that accurate when measuring heart rate, it’s not clear how well this $249 harness would actually work. There weren’t enough backers to support the project to get it funded on Indiegogo.

If you don’t know how to fit your puppy’s collar, check out this helpful guide.