This song is very clever with its lyrics. Some translation notes below.

Gokumi: Kumiko Goto, an 80’s idol
Kabuchimono: Flamboyant samurai gangs of the Edo period, some historians believe the yakuza to have originated from them
The chorus contains some word play on Japanese historical eras:
– Image (imeeiji – イメージ) sounds like Meiji (明治)
– Constrasting (taishouteki – 対照的) sounds like Taishou
– Show wa (Show は) : Shouwa
– Serene (heisei – 平静): Heisei
Wasshoi: dictionaries translate this to ‘heave-ho’. May be used for example, if you were doing a strenuous task.
Like a Dragon: as in Ryuu ga Gotoku, name drop of the series title

Also an ammendment, the second line of the first verse should say “not uncool” rather than “uncool”

WACOCA: People, Life, Style.