Sometimes it’s all about the casting. Hiroya Shimizu and Mahiro Takasugi have an on- and off-screen bromance that stretches back to when they appeared together in the 2012 TV drama “High School Entrance Exam.” Their rapport is one of the best things about “Oasis,” a mostly generic crime drama by first-time director Takuro Iwaya, who also wrote the script.

Set in the filmmaker’s native Nagoya, it’s a familiar tale of childhood bonds clashing with gangland loyalties, enlivened by offbeat touches where the quirkiness doesn’t always seem to be intentional. Hiroto (Shimizu) and Kanamori (Takasugi) grew up together, until a violent rupture sent them down different paths. Now the former is an enforcer for a local yakuza family, while his old pal has hooked up with a less tradition-bound gang.

Both of them seem resigned to playing the roles they’ve been assigned; Hiroto, in particular, treats his vocation with the seriousness of a young executive on the corporate fast-track. However, his dedication starts to falter when he’s reunited with Beniha (Marika Ito), a damaged young woman who was once part of their teenage friendship group.