Mint in Ikebukuro is actually two floors. The floors aren't connected; if you want to go up to the 2F store you have to exit the 1F store and go upstairs and enter the other half, which is odd but normal for Japanese buildings.
Mint Ikebukuro 1F
Mint Ikebukuro 2F
("Trading cards, sports figures")
Location: 東京都豊島区東池袋1-28-6 (Google Map)
Tokyo-to, Toshima-ku, Higashi Ikebukuro 1-28-6
Hours: 1F: 11am - 8pm (every day, both floors)
Directions: From the JR Ikebukuro station, pretend you're going to the Sunshine 60 building. Take the "Sunshine Exit", which is on the east side of the station, and walk forward until you can bear left and follow the crowds crossing the big intersection to "Sunshine Road" (there'll be a Lotteria on the left and a Sanrio Gift Gate on your right once you enter the correct street, also a Shakey's on your left). Walk down Sunshine Road for 3 blocks and turn right on the corner with the Sega arcade, the Matsuya, and most importantly, the 50-yen arcade with all the UFO catchers. Go halfway down that block and it'll be on your left.
Size / Type: Standalone store, relatively huge, TWO FLOORS!
People: Eh. I was sort of put off both by the proprietors and the clientele but I might have just been there at a bad time, plus I got angry listening to them talking about how they wished they'd gotten Ogasawara signed stuff when he was on the Fighters because now they're worth more with him on the Giants grrrrr.
Stock of interest: The first floor is mostly soccer stuff with a handful of baseball stuff, nothing too exciting, some random packs and a lot of rookie cards, some figurines, a bit of soccer memorabilia and some MLB stuff.
The second floor has lots of boxes full of single cards you can look through, plus ample counter space to do so -- two full counter/bookcases of baseball card boxes. Handful of interesting cards from the early 90's, lots from the later 90's. Team sets not as well-organized but they make up for it by having more sets of stuff to poke through. This store had a full array of Rookie Edition sets from both this year and a few past years, including lots of the insert cards, and team rookie sets. Pretty big amount of single cards labelled as normal, which means they cost 50 yen each, and that includes way old stuff too.
Lots of packs but nothing too old or exciting, just a lot of 2007 team packs and they did have 2007 1st Edition, at least. Also plenty of the normal assortment of MLB stuff.
The thing is, the other two counter/bookcases are full of soccer cards and bikini model cards, which makes for some interesting clientele. The other problem is that the cases are pretty close to each other -- if one person is standing there looking at cards, it's difficult for another person to squeeze by them to look at other stuff.
What I bought:
Shigetoshi Hasegawa 1992 BBM (50 yen!)
Masahiro Tanaka 2007 Rookie Edition (300 yen)
Masahiko Morino 2007 Rookie Edition insert card reflector (250 yen)
Two packs of BBM 1st Edition (210 yen each)
I got a Shogo Akada signature insert card in the BBM 1st packs, plus a Munenori Kawasaki, plus a Carp Yuuki Saitoh, so I was happy with that.
Logic on the Masahiro Tanaka card: basically, I didn't care if I got the entire Rookie Edition, I just wanted one card from each team since they have a rookie group photo on the back of all of them, and after like 3 packs, the only team I had no cards from was Rakuten. So, I had decided I would stop buying packs and just buy one Rakuten card -- BUT, if I was gonna spend 50 yen on like, Naoto Watanabe, why not just splurge the 300 yen for Masahiro Tanaka? And then I made the mistake of looking through the Rookie Edition insert cards and I found the Morino card in with the "1997 Rookie Special" reflectors and... and... yeah. I actually had looked for an early Morino card in the 1997-2000ish singles but didn't find any, sadly.
Something seriously surreal in this store was seeing, in the early 1990's sets, say, a Takashi Saitoh 1993 card for 50 yen next to a Kazuhiro Sasaki card from the same set going for 800 yen. Also lots of early Motonobu Tanishige cards, when he was on the Baystars. (There really were a lot of great players on the Baystars at one point, but they all moved on elsewhere, it seemed.)
(Man, now I'm wishing I'd really taken notes on what some of these places had, but I'm mostly going on my memory of what I looked through, plus what things I thought about buying. Anywhere that still had BBM 2007 1st, I bought a pack, too.)