My wife is Thai, and before we came to settle permanently in the UK, we lived for a few years on the island of Ko Lanta, where she worked as a medic, in a traditional wooden house near the sea.

When we had been married for six months, her younger sister Kanda came to live with us. She had just finished college and was looking for a job. She was 23 years old.

Kanda was similar to her older sister in many ways. She had the same slim figure and long chestnut coloured hair. The same perfect complexion. The same wide dark eyes and cute plump cheeks. The same soft hands.

But her personality was opposite to my wife in almost every way. She was lazy, playful and spontaneous. She liked to hang around the house all day listening to pop music. She had beautiful mischievous eyes. She was always up to no good.

The difference in character caused plenty of tension between the two sisters but relations between Kanda and me were always relaxed and easy going. My wife worked long hours at the clinic, so Kanda and me were often left to our own devices. We went shopping, cooked, watched TV and walked on the beach together.

From the beginning, there was a relaxed physical intimacy between Kanda and me. Thanks to the Thai climate, and the house’s crappy air-conditioning, we were always scantily clad around the house. I never wore more than shorts and a vest, and Kanda wandered around in the flimsiest cotton shorts. It was the only way to stay cool in the fierce tropical humidity.

When we were watching TV, she liked to lie on the couch and rest her legs on my lap. And it only seemed natural for me to put a hand on her knee, to tickle her feet or squeeze her thighs. When I was at my desk she would come and sit on my lap, casually wrap an arm around my neck, and tell me some gossip about her day. Despite her basic level of English, Kanda loved to chat away. When I misunderstood something, she got beautifully frustrated, called me an idiot and poked me in the ribs, then got up to go and sulk in another part of the house. Then I would have to go up to her and stroke her arms or her hair, or give her a kiss on one of her plump cheeks, and tell her I was sorry. The game was so delightful that we played it many many times.

One evening, she came back from meeting a friend very upset and went to her room without stopping to chat. When I followed her in, I found her lying on the bed in tears, and sat down next to her.

“What’s the matter, Kitty?” I asked, using her pet name.

She didn’t want to talk at first, but as I stroked her hair, she gradually opened up and told me what happened. Then it all came out. The argument with her friend. The trouble with her sister.

I caressed her hair, then her arms. And the more I did so, the more she relaxed and opened up to me. So I stroked her back and pinched her waist, and she didn’t seem to mind. So I tickled the back of her thighs and pinched her bottom. And she didn’t seem to mind, but after a couple of minutes she got up to take a shower.

The pattern repeated itself. She would lie on the couch and rest her legs on my lap, and let me lazily fondle her for half an hour at a time, and if I got aroused and her feet happened to brush against my groin, she didn’t complain. But after a while she would always get up and move away.

Then one evening in midsummer, things went further. My wife was away in Bangkok for the weekend. Kanda and I had whisky at a beachfront bar early in the evening, then came back to the house. She was very giggly as we walked back and I had to help her along. We sat on the beach for a few minutes to look at the sunset and she put her head on my shoulder. As soon as we got into the house, without saying anything she gave me a big hug and held me for a long time. I felt her breasts pressing into my chest and I felt the hollow of her groin against mine, and I let my hand rest casually on her bottom. Then she ran off to take a shower. In my room, I took off my outdoor clothes and stood naked in front of the air conditioning to cool off. I jerked off for a little bit, then I put on a pair of cotton shorts.

When I came out of my room, Kanda had finished her shower and I saw her bedroom door was open. She was lying face down on the bed wearing only her panties. I went in and sat on the edge of the bed and stroked her hair. Then I ran my hand down the smooth skin of her back and just rested my hand on her hip. Without warning, Kanda sat up and kissed me on the lips. So I held her head in my left hand and kissed her. And I ran my other hand over her body and squeezed her firm young breasts. Then Kanda ran one finger down my chest and over my shorts. Then she slipped her hand inside my shorts and wrapped her soft fingers around me and fondled my penis while we kissed.

I let her play with me for a few minutes, then I pushed her gently back onto the bed and pulled down her panties. I kneeled down by the side of the bed and pulled her towards me and Kanda opened her legs and showed me her smooth hairless pussy. I pressed her legs wider and kissed her thighs and her butthole and licked and kissed her cunt. But she was already soaking, so I took off my shorts and put a blanket on the floor and kneeled between her legs. I teased her with the tip of my cock until she begged me to have her.

All night long, I enjoyed her supple, nubile young body. I took her on the bed with her legs spread open. I took her bent over the kitchen table, her butt slapping against my loins. I took her sitting on my lap, my cock deep inside her, my face buried in her ripe breasts. In the shower, with a finger in her arse and two in her pussy, I made her squirt. I came inside her five times that night. I came all over her tits and belly. I came in her mouth as she knelt before me. And I brought her to panting orgasms loud enough to wake the neighbours.

When the first rays of dawn touched the house, we ran down to the deserted beach and swam naked in the green waters of the Indian Ocean. Then we came back to the house, and I took her to my marriage bed and we dozed all day in one another’s arms.

In the evening, we were woken by the headlights of my wife’s car drawing up outside. Kanda, like a thief in the night, slipped from my bed and went back to her own room. She stood there in the doorway, watching me, until we heard the key turn in the front door.

And then I put on my shorts, and straightened the bed, and went out to greet my wife.