Maru has the following etched into the handle of his bat: C9 B.
The C9 is for Carp and uniform number 9, or Maru. The B indicates the number of times he has made changes to his bat since he joined the team. In this case, B means he made a change to his bat once (he got a thicker handle).
Source: Nikkan Sports 5/30/2016
Maru recorded the sixth multi-homer game of his career on July 6, 2017. The two home runs gave him twelve at Mazda Stadium in 2017. Only two other players have hit more at the stadium in one season: Brad Eldred hit twenty in 2014 and Seiya Suzuki notched fifteen in 2015. Maru has now hit fifty career home runs at Mazda Stadium. Only Eldred has more with sixty.
Source: Nikkan Sports 7/7/2017