Purchase
You give a shellfish to a lifeguard to purchase their services. You think lifeguards are interested in normal money? Come on, they're obviously out there using shellfish for their purchases. It's only natural, given their seaside habitat.
Imagine the grooved surface of a shellfish shell as you press it into the hand of a lifeguard. Congrats, you've just completed a purchase. Uh… what'd you get?
こう
None
None
This time you purchase some こういち goods. You know, since you're such a fan. How else can you show love in this world, if not through purchases? The lifeguard hands over a little haul of こういち plushies and figurines. Nice.
And it's totally because those こういち goods are so valuable that the lifeguard accepts shellfish for them. Has nothing to do with the fact he couldn't get real money for them, okay? Hint: When you see the "lifeguard" radical, the reading is probably going to be こう.