At the same time, it is reported that the BOJ has no intention to surprise bond traders. I mean, not to say that taking such a step is entirely surprising. They will likely do so while reaffirming that they have the flexibility to step back in again, should market conditions dictate them to do so.
In any case, this was always going to be the next move before they get to raising interest rates again. The latter looks to be on the cards for July potentially next.