There is one precise moment when I question the wisdom of taking my two young daughters to visit the Snoopy Museum in Tokyo's Roppongi district.

It comes as my 2-year-old kicks her shoes off and makes a barefoot beeline for a fire extinguisher in the corner of the gallery, just as her big sister, aged 4, jumps up to touch an original 60-year-old comic strip on the wall.

With unfortunate timing, I had just asked the ever-patient museum PR, his eyes following the children, about the museum's target age group: "Um. Maybe 30 to 50-year-old women are the most common visitors," he replies. Fortunately, he adds quickly: "Although we are keen for children to visit, too."