There were 14 card sets issued by companies other than BBM or Calbee this past year. This is down quite a bit from the 19 that were issued last year.
The main reason for the drop off can be attributed almost entirely to Front Runner (Frontier International). After issuing 11 team based box sets in 2014, they only released four sets in 2015 and none after April. They released the "Giants Game Used Bat" set in February, the Lions and Buffaloes "Heroes And Rookies" sets in March and the Baystars "Heroes And Rookies" set in April. Not only were their no releases from them after April but Epoch issued at least two sets late in the year that look like sets that Front Runner would have released. I do not know if Front Runner went out of the card printing business, if they got bought up by Epoch or whether this is all part of their marketing plan. We'll see if they reappear this year.
Epoch on the other hand increased the number of sets they did from five in 2014 to seven this past year. They started in march with an OB box set celebrating the 30th Anniversary of the Tigers first (and only) Nippon Series championship in 1985. They followed that up in June with a box set for the Carp that celebrated the 40th Anniversary of the "Red Helmet" era for the team. This set was the first Epoch set in recent years to feature active players as well as OB players. They released another set in June in conjunction with the Japan Baseball Promotion Association (JBPA) called "National Record Holders" which was an ultra high end set along the lines of BBM's "Master Of Insert" set. Each 15,000 yen (~$125) box contained one pack of five serially numbered cards including two autograph cards. Moving into the fall, Epoch published three team based box sets that only contained active players - no OB players at all. The sets were Baystars "Game Used Uniform", Swallows "Victory Memorial" and "Dragons X Mizuno". The Baystars set seems very similar to me to some of the Front Runner sets from 2014 (including the "R" for rookie indicator on the cards) and Dragons set continues a theme done by the Carp and Marines in 2014. The final Epoch set was released in December and it was another ultra high end set done with the JBPA. Called "MVP Of The Year", this set follows the same MO as their earlier ultra high end set - 15,000 yen for a box containing one pack of five serially numbered cards including two autographed cards.
Sports Graphic Number issued one set this year, the same as they did last year (I mistakenly thought that a set issued by the Swallows last year was issued by them). As usual, their set was dedicated to a single player - this time is was Yoshitomo Tsutsugoh of the Baystars. Also as usual, this was a pack based set that featured very little text and lots of "puzzle cards" - pictures taking up multiple cards.
The final two card sets I want to list here are team issues but they appear to have been distributed nationally* - they are listed both by Jambalaya (which was located in Fukushima most of the year but moved to Hachioji in Tokyo Prefecture in November) and Hot Box (which I think is located in Matsuyama in Shikoku). The first set is a team set for the Eagles while the second set highlights three players from the Swallows that were selected by a fan vote - Tetsuto Yamada, Shingo Kawabata and Shohei Tateyama. The Swallows set looks so much like a Sports Graphic Number set that I thought that the set they did last year actually was a Sports Graphic Number set.
*So including team issued cards on this list is kind of problematic - I mean I have cards from the Buffaloes and Lions fan club sets from 2015 and I'm aware of ones for the Hawks and Tigers. I assume other teams have them but I have no idea what they are. So I'm pretty much only listing sets that appear on Jambalaya and Hot Box's websites. Don't ask me what I'll do if a set shows up on one but not the other...