Reminds me of a oneshot with the same kind of ending, iirc from the author of the "something something lonely girl" series. Scratch that, it's kabocha.
There are hearts on the right side, but, also, this is probably translating 'kokoro' which can mean heart as in the organ, but usually is describing the soul or spirit or mind, so this isn't necessarily about the physiological heart.
There is the one where one of the girls goes "Hey, can you meet me in a secluded spot later, I want to confess." and then realizes what she blurted out and retreats in a hurry.
There is the one where one of the girls goes "Hey, can you meet me in a secluded spot later, I want to confess." and then realizes what she blurted out and retreats in a hurry.