From the outside it's just another concrete building rising up nine or 10 stories on a downtown Tokyo street. Inside, it's no more impressive — until Shinichiro Tatsumi opens the well-secured door to his own, private Bob Dylan heaven.

What confronts the visitor, Dylan fan or not, is a breathtaking sight. Occupying a room some 15 meters long and 5 across, it is what Tatsumi confirms as being certainly the largest collection of Dylan material in Japan. And who's to say if not in the world.

Truly the eyes pop, and pop again and again, as the brain tries to take in the scale and scope of this trove. Over almost 35 years of collecting, Tatsumi, 49, has now assembled here a mind-boggling 2,500 copies of officially released vinyl albums by Dylan, including compilations and promo albums and ones related to his sidemen, as well as around 1,000 copies of comparative vinyl singles. And even though Tatsumi can instantly lay his hand on anything here, each and every item in this one-room cornucopia is also meticulously documented on his computer.

That's just as well, because along with those vinyl records from all over the world, there are some 2,000 officially released CDs, hundreds of DVDs and — wonder of wonders — nearly 450 bootleg CD albums which, together with CD-Rs, DVD-Rs, cassettes and DAT recordings, cover an incredible 2,500 of Dylan's roughly 3,000 concerts in the more than 55 years he's been performing in some 30 countries.

All this started, says real-estate executive Tatsumi, a graduate of the commercial science department of Meiji University in Tokyo, because when he was young he liked Japanese folk musicians such as Takuro Yoshida and Yosui Inoue, and on late-night radio programs they sometimes cited someone called "Bob Dylan" as a big influence on them.

"Then in the summer of 1977, when I was 15, I heard 'Blowin' in the Wind' on one of those programs," Tatsumi recalls, "and instantly it came as a huge shock. I was so amazed by his voice."

The next day, off he went to buy Dylan's 1963 album, "The Freewheelin' Bob Dylan," which features "Blowin' in the Wind." Soon, by his own admission, he was "playing catchup," as by then, with the previous year's live "Hard Rain," there were already 19 official Dylan albums out there.

Since then, he's amassed not only all that Dylan music, but the countless (carefully cataloged) books, magazines, T-shirts and other clothes, posters, ticket stubs and assorted Dylan-related bits and bobs (from ashtrays to chocolates) that surround us in this astonishingly well-ordered room. For Tatsumi, playing catchup has truly become a labor of his self-described "love" — a "life's work" he happily lays bare in this recent "70th Birthday" JT interview.

Why was Bob Dylan's voice so special for you?

It was completely different and it touched my heartstrings. It's impossible to put into words, but it got under my skin and has always stayed there. His timing and pausing, and the rising and falling tones in particular, still sound perfect to me. Though some people have always said Dylan can't sing, I am listening to his music with my soul, not just my ears.

When did you start collecting?

I think I was born with a mania for collecting; when I was young, I collected menko game cards and stamps. Then, soon after I bought "Freewheelin' " when I was 15, I came across a Dylan bootleg in a secondhand record shop. I'd never seen a pirated record before and I was so surprised they existed. That one, of a concert in New York, was titled, "Live 1964: Concert at Philharmonic Hall." The sound quality was good, and it was exactly my cup of tea, with its simple acoustic guitar music, so I bought it. It was like a taste of honey that gave me a craving for these bootleg treasures that let me hear his many different voices and arrangements live. And to this day, I'm still collecting bootlegs of Dylan.

However, back then 34 years ago, there was no Internet or downloading, so I'd go to secondhand record shops around Tokyo every weekend hunting for Dylan bootlegs. As I did so, I also came to realize that there were major or minor differences between official pressings from different countries, such as the cover designs of the same album from Japan, America and Britain, for example. That discovery was a real thrill for me — it was my first grade, the starting point of my collector's history — and I began seeking out different pressings from those three countries.

A few years later, I started to find records from other countries, such as Italy and Germany, at bigger new secondhand shops that were opening, like Disk Union. Though the music was the same, they were completely different again — and for me, that was my second grade.

Then, when ordinary people first got computers in the mid-'90s, that opened my eyes to pressings and covers I'd never seen before from countries such as Brazil and Argentina. In particular, through the Internet in 1995, I bought an Argentinian "Nashville Skyline" with a very rare jacket titled "Lay Lady Lay" on the front and a photo from Dylan's Isle of Wight concert in Britain in 1969 on the back. That record opened my eyes to a wonderful new world and was the trigger that took me to my third, ongoing grade as a serious collector. Even today, that's still my special one.

What's the satisfaction of collecting?

There are many satisfactions. First, I want to listen to Dylan's music that wasn't released officially. So, for instance, I can find out how the singing and playing on his 1978 world tour changed at different shows and compare them with the tour's official double album, "Bob Dylan at Budokan."

As many people know, Dylan changes his set lists for every show, and often the musical arrangements, so I just want to listen to as many live concerts as possible. That was my first aim.

Also, because of my English level, I'd have had a huge wall to climb to become a researcher of Bob Dylan, and there were already experts in the field such as (Toshiyuki) "Heckel" Sugano here and Michael Gray in Britain. But I am good at collecting, so I became a collector of Bob Dylan — a never-ending collector! (Laughs.)

How much time do you now spend on collecting?

(Laughs.) I have my main job, so it's difficult to answer that in case any of my employees read this!

However, I try to take an hour at least after work and before I go home each day to sit down in front of the computer here and check on Dylan information. After all, I set up this room for my Dylan collecting and collection, so it would be a waste of my time and money if I didn't make good use of it. Really, though, this is my playroom — I'm not a researcher, so all this is for my amusement and it's not like work at all.

At home there are no Dylan-related things, because my son, who's 15 and likes music, isn't interested at all. Neither is my wife, or my parents with whom we share the house — so we listen to J-pop.

How much do you think you've spent on everything here?

(Laughs again.) I can't say — because of my wife. Anyhow, the most expensive thing is a signed, limited-edition print I bought at an exhibition of his artwork in Tokyo last year. It was almost ¥200,000.

What are some special things for you here other than recordings?

(Tatsumi opens some files.)

There's this. When Dylan played at "Aoniyoshi," a Unesco charity concert at Todaiji Temple in Nara in May 1994, I got Dylan's and his manager Jeff Kramer's autographs at the Hotel New Otani in Osaka where they were staying. But Dylan was carrying his bag, so he wrote this with his left hand.

Another high point of my collecting career was when Sony Music Japan decided to issue a limited pressing of Dylan CDs in paper jackets around 2004, and they asked to make use of my collection for the covers' artwork. So they printed "Special thanks: Shinichiro Tatsumi" in all those liner notes. Sony asking me to be involved in a Dylan project — that's my happiest memory. It also led to the John Lennon Museum in Omiya, Saitama Prefecture, contacting me over a planned Lennon and Dylan exhibition — so, some of my records were displayed there for almost six months.

Do you have any particular target for your collection?

Someday, I want to get one of the super-rare handful of original test or promo pressings of "Freewheelin'." There were all sorts of hassles inside and outside (record label) CBS about which tracks to include on that album. In the end, four songs from those very first copies were replaced on the album that was released in May 1963. I've heard it said that — even if you could find one — any "Freewheelin' " with "Talkin' John Birch Society Blues" on it, which was one of the tracks omitted, would cost at least ¥1 million.

Have you ever considered opening this collection to the public?

It's my pleasure to invite my close friends to enjoy the treasures in my playroom and talk about Dylan together, because this is my life's work and I expect to be doing this till I die. However, I've no thought to open this to the public. If I did, there would be so many complications, and I don't want to be bothered with all that at the moment.

Which is your favorite Dylan song or album?

I basically love all his music. What I listen to just depends on how I feel. If you were to push me, though, I'd have to name "Forever Young" as my favorite song, without any doubt, and "his next one" as my favorite album — or "Freewheelin'," which is today's answer. However, one of my all-time favorite lines is, "Ah, but I was so much older then / I'm younger than that now" from "My Back Pages" on 1964's "Another Side of Bob Dylan" album. It's very hard to choose.

When did you first see Dylan in concert?

On his second visit to Japan, in 1986, I saw him twice in Tokyo. Because I didn't see him when he came here the first time, in 1978, I think that frustration pushed me more to concentrate on my Dylan collecting in those days. But since his third visit, in 1994, I've been to all his concerts in Japan — in '94, '97, '01 and 2010.

If you met Dylan face to face, what would you like to talk with him about?

I've no idea right now. But it's a dream of mine that one day he may come here, into this room, and ask me what I'd like to hear him play. And I'd love to have a photo taken with him one day.

Do you have any 70th-birthday message for him?

Congratulations! May you stay forever young — and please keep performing on stage as long as possible, and returning to Japan as often as possible.