2008 was the only year where Morning Musume had no changes (Graduation, New members)
Considering this, I wouldn’t be surprise if 2016 have some kind of change (Graduation) as well
I just don’t see them keeping things the same for more than a year
But, First Sentai Black Leader 19 years see: in Ranger Wiki
Kouichirou is the president of the "Digital Research Club" of Moroboshi High; he was one of four students (alongside fellow students Shun Namiki, Chisato Jougasaki and Miku Imamura) investigating strange occurrences and technology being created at the NASADA plant in connection to the works of I.N.E.T., unknowing that Kenta Date, a fellow student, had already been recruited for their research. When the Nejireija began their invasion pre-emptively, the four students and Kenta were all given Digitizers and the task of becoming Megarangers in order to battle the invaders from the twisted realm.
The Twisted Invaders After the five became Megarangers, Kouichirou invited Kenta to join their club due to their current common connection, even though his grades are lacking.