I think hello has many translations with japanese in multiple situations. U, however, can say Konnichiwa formally. When u wanna use "hello" such as greeting in Japan, u just do a vow softly, wave a hand or say something such as "Yo!","Yaa","Oo","Ou".....etc and someone whose name u are seeing.(Basic translations are Chi's. they are perfect.)
We don't always say words with greeting like "hello". It is cuz different cultures.:)