I... Luthiers (21st C.)

(more translator fun), but from what I can work out he, (if this is the right person? he might just be a film director), started in 2008 making the rectangular Cheese themed Ukulele. At the same time a film of some kind was being made and it featured this Ukulele quite heavily. The film was released in 2009 and was called Paititi (or something similar) and followed actress Yoriko Horaguchi and her unique Ukulele group and possibly included issues around cervical cancer. Since then there have been lots more Cheezy Ukes made, (called Mr. Cheezy) both as Sopranos and Concerts with 14 frets to the body, using a number of solid woods and often a pearloid fretboard. I have never seen anything that isn't a Cheezy Uke.

Stanley Ishikawa is based in Pearl City, O'ahu, and creates Concert and Tenor size Ukuleles, usually out of solid koa. I don't know much about him but he started making Ukuleles some time before 2005 

From what I can translate, (and I may as ever have his name the wrong way around?) he studied under / worked for a well respected luthier in Kyoto called Chaki before setting up on his own in 2015, (possibly in Kyoto too?) From what I have seen so far he only makes Sopranos.

From Kapolei, Oahu, and given his apparent output of less than 5 instruments a year I doubt he is a full time luthier but I haven't found much on him. I think he went to the University of Hawaii and is a member of the luthiers guild of Hawaii. I know he has been making Ukuleles since before 2007 and all of the models I have seen have been Tenors. 

Based in Suginami-ku, Tokyo, he started making musical instruments in 1978 and started using the Acoustic World branding in 1981. I have seen a number of instruments of his that have The Iwamoto on the headstock rather than Acoustic World, (I think these are his top instruments but I'm not sure?). His main instrument appears to be the Mandolin but he does make all the usual chordophones including Violins and Ukuleles. From what I can see he has a standard Ukulele catalogue based loosely on Martin with a choice of Soprano, Concert or Tenor, s1, s3 or s5 levels of decoration, and 12 or 14 frets to the body.