In April 1998, a piano bar named "INDIGO" was opened in a corner of Nishi-Azabu.

Eriko Ohara and her closest friend Yumiko Tsuzuki were the young co-owner of the extremely luxurious place. The members of the quartette #4 with no name at that time helped the finishing of the brand new bar as close friends of both ladies and as regular customers/supporters to be, except Shigeo Kurimoto who left the country for his overseas business assignment missed the inauguration party and privilege to enjoy the place as one of the regular customers by only a few days gap of schedule, however Shigeo Kurimoto was comfortable enough as he had been very well informed of what is going on in INDIGO by E-mail bulletin on day-to-day basis.

Later the collection of all bulletin was made into a thick book!!

As Beethoven became unwell a while ago the piano accompaniment and arrangement for the group had been undertaken by Eriko Ohara, resident pianist and co-owner of the bar and the group deemed her as musical director. Or it would be better say the group's musical director opened her own Piano bar with her friends. The three guys started their training regularly in INDIGO. The other customers of the bar began to recognize those three guys as a group of regular customers but very unique or odd as they are always sitting around piano played by Eriko Ohara and sing jazz tunes in chorus.

As they had no name the customers who want to listen to their chorus they had no choice but request "usual chorus by ojisans". Four guys at the end of the day got used to what the other customers call the group and took it as their name - "THE OZ SONS" - not The Sons of Wizard OZ which is bit too smart for them, while "THE ODD SOUNDS" is too honest. One of the members said "THE OZ SOUNDS" may be right name but finally they took the direct word of the other customers straight away.

Actually the group got the name "THE OZ SONS" only in November 1999 till that time they needed no name as nobody cared their name but an invitation to the concert stage of The Three Graces suddenly put them in need of their own name. Another amateur chorus group was invited as well for the stage. Their name is "THE DANDIES FOUR"!!. They loved to say "Name? Who cares" but this time they have to care complaining "Then how Three Graces could introduce us on stage? "A chorus group of three old men usually singing/drinking - drinking/singing - whichever they like - in a piano bar" following the announcement of three smart words "THE DANDIES FOUR" ??" They made up their mind to have a name leaving the big difference between the two groups. THE DANDIES FOUR had four sets of tuxedo for each, while pity "THE OZ SONS" finally got name but no uniform wear for the stage. Still they have got none at all even today.

What THE OZ SONS has and the others may not is their own decent studio equipped with full digital machine for exclusive use. That must be the thing "THE OZ SONS" care but not clothing. Quite recently THE OZ SONS got four pieces of bow-tie!! - a big change.