I got this plant from some Japanese and it's supposed to be from Africa. Name anyone?

Question

I can describe what the plant does but I don't know the name. It's a tree it takes about 10 years to grow from a seed to a tree. It sells for about 10,000 yen in Japan. The seeds sell for about 300 to 500 yen each. When you suck on the seed. You get a sweet sensation from sour things for about 15 minutes. Meaning Lemons and every sour tastes sweet. If anyone knows what this seed/plant is called let me know!

Thanks!

Answer 1

It is called Miracle Fruit or a.k.a. Miracle Berry

Synsepalum dulcificum  

a.k.a. Miracle Berry

A relatively tasteless berry with an amazing side-effect. After eating one miracle fruit, sour things will instantly taste sweet. Eating even the sourest of lemons, one will taste only sugary sweetness. The effect lasts an hour or two. The miracle fruit is a remarkable natural sweetener that is virtually unknown to much of the world.