Ko-(knee)-chi-(wah) She-my
(then add [-san(formal or polite)] or [-chan(common and familiar)]
So, it would be
konichiwa Shimai-san!
or
Konichiwa Shimai-chan!
And only when you are a very young (still in early-middle grade school) or a Girl (of any age) you can say
Konichiwa Shimai-saaaaan!
or
Konichiwa shimai-chaaaaan!
Konnichiwa is 'hi' in Japanese.
You may say 'hoka no hi' or 'betsu no hi.'
hi ming
hi no tora
Hi no akuma
Hi no bakuhatsu
yami no hi
You may say 'imouto.'
hola hermana
zan zumi
it's konichiwaIf you want to say hi in the morning, say, Ohio gozimasu
Kamon achen Apu