Tomomi's "Bluetus" seems loosely based on a Squier Vintage Modified Jazz Bass, although it's kind of an amalgam of several different sub-models and has regular vintage (not "modified") Jazz Bass knobs on it. Like the other Scandal signature instruments, this bass made its debut at their Budokan show in March of 2012, and it's been a staple at their concerts ever since. I saw it in person again just last month at their show at Fujita University. She doesn't use it for every song - unlike Haruna with her Skullsilver Telecaster and Mami with her black Strat, Tomomi doesn't really have a "main" bass, and if she does it'd probably be her navy blue Fender Precision Bass. But she still uses Bluetus often.