You carry a cross across a rice paddy with a heart on it to return a favor for your friend. The heart needs to be purified so that’s why you have it on the cross and your friend lives on a rice paddy farm so that’s why you’re running through that. The favor you are paying your friend back with is getting him this heart. He needs a new one and you’re providing it.
You arrive at your friend’s place and you can finally return the favor you owe him by presenting him with the heart. “Eh (え)? What’s this? I didn’t ask for this!” “Eh!?!?” you reply. Apparently he didn’t want a real heart, he wanted a candy one. He wanted a Valentine!