Junko is out of Lady Zuzu (Dynaformer), who was placed in two Grade 3 turf races in the US. He is a half-brother to the winners Warzuzu (War Front) and Zileo (Galileo). Lady Zuzu is a half-sister to the sire Optimizer (English Channel), a multiple graded winner whose wins include the Grade 3 Fair Grounds Handicap and who was three times placed at Grade 1 level. Two other half-sisters were placed: Cello (English Channel), dam of the stakes winner Cellist, third in the Grade 1 Belmont Derby, and Pick Me (Horse Chestnut), grandam of the Listed-placed Sister Bridget.

Second dam Indy Pick (A.P. Indy) was a winner. She is a half-sister to Finder's Fee (Storm Cat), winner of the Grade 1 Matron Stakes and the Grade 1 Acorn Stakes, and to the stakes-placed Treasure Island and New Way, both by Danzig. Finder's Fee is the grandam of Feathered, a Grade 3 winner and runner-up in the Grade 1 Starlet Stakes, and the third dam of Flightline (Tapit), Horse of the Year in the US, unbeaten champion, multiple Grade 1 winner and sire.

Third dam Fantastic Find (Mr. Prospector) was a Grade 1 winner.

The wider family includes further Grade 1 winners such as Heavenly Prize, Instilled Regard, Queen Goddess, Oh What A Windfall, Dancing Forever and Bigger Picture.