I must have been about 7 years old that summer at Baa-chan’s. I loved to play with my brothers Tetsuo and Hiro alongside the canal that ran behind our grandma’s house. This was where we built forts, ate mangoes we stole from her neighbors’ trees and fished for tilapia.

Then one day Tetsuo found the tracks in the mud. They were webbed, like duck’s feet, and about the size of a 3-year-old child’s footprint.

Hiro mentioned this to Baa-chan, who became very alarmed. She told us the tracks were made by a Kappa, a water sprite, who was considered very dangerous in Japan.

"Kappa wa kodomo wo narrate, oboraseru yo! Abunai kara moo atchi de asobanaide! The Kappa will hunt you and drown you — it’s dangerous, so stop playing there!"

Instead of heeding her warnings, we decided to try and capture the beast by setting a simple box-and-string trap baited with its favorite food, cucumbers.

Hiding in the bushes that starlit August night, my brothers and I took turns sleeping and keeping watch. When the moon was at its zenith, Hiro suddenly shook us awake and pointed at a small shadowy figure creeping into the trap. He pulled the string — the creature was caught!

Whooping with excitement, we armed ourselves with guava branches and slingshots and cautiously lifted the box. It was a mysterious sight: The creature was a slimy greenish yellow with a saucer-shaped indentation on the top of its head and something like a turtle’s shell on its back. Its hands and feet were webbed and it was munching away at a cucumber with its beak mouth.

Its large, frog-like eyes gazed at us balefully.

So this is the Kappa! I thought. Baa-chan said that if you get it to bow, the water will spill out of its head-dish, rendering it powerless. So, like the good Japanese boy I was brought up to be, I said, "Konbanwa, Kappa-san!" and bowed.

The creature’s eyes widened and it crept out of the trap, straightened up and bowed back — spilling the water from its headdish.

I forget what games we played with the Kappa, but by the time the morning sky started to turn pink, my brothers and I were quite sure that Baa-chan was wrong about him.

We bid the creature goodbye, leaving it alone on the bank of the canal as we packed up our gear and headed back to Baa-chan’s house. Upon our return, she asked how our hunt went and we told her. She turned paler and paler as we relayed our tale, and then she asked if we had replaced the water in the Kappa’s head-dish. We had not.

"Aiyah! Hurry back now! Before too late!"

We hightailed it back but our Kappa now lay lifeless. Its head-dish empty, it had been too weak to climb back into the canal. We slid the poor body into the water and watched it float away. Trudging back to Baa-chan’s, I swear I heard a cry of anger emanating from the canal.

That night, a commotion and murderous screams were heard from Hiro’s room. When Tetsuo and I got there, wet, duck-like footprints were everywhere and Hiro was gone. Tetsuo and I grabbed our slingshots while Baa-chan called our parents in Manoa, and we headed out to find the creature that had taken our brother.

We went straight to the place where we had captured the Kappa and came upon Hiro, struggling in the grasp of a larger, stronger-looking Kappa. It spoke to us in a rasp: "You love your brother? So I loved mine. Now I have no one, while you have each other. Life for a life. He replace MY brother."

I could not let my younger brother suffer. Which is why I took Hiro’s place.

As I sit here, in the canal, I know from the warming temperatures that Tetsuo and Hiro will come again, as they have every summer since that night, to spend time with me … their brother, who joined the ranks of the Kappa.