For several of my years in Japan, the word "tetrapod" was one of those katakana English expressions that would pop up in conversation or on TV once in a while which would have me materializing question marks around my head. Remembering my derivations for prefixes and suffixes, I figured that the word was referring to animals with four legs (or me after a bender) which was indeed true. However, the context I heard it in made it quite clear that the Japanese usage of the word wasn't moving toward the quadrupeds. Not surprised by the confusion, though. Quite a number of gairaigo （外来語...foreign loan words）have meanings in Japanese society that don't quite match the original definitions.
One of the other sources for the hearing of "tetrapod" was this breezy country-style tune by singer-songwriter aiko at the turn of the century. Again, at the time "Boyfriend" premiered in September 2000, I still didn't quite know what the term meant but it was included in this song about going out with the beau. The Osaka-born girl-next-door with the spunk was more than happy to prance about on stage describing a sunny day in a happy life.
It wouldn't be for a little while yet that I finally found out that the tetrapod was referring to those four-legged structures that lined many of the shores in Japan like a bunch of giant concrete jacks. I used to call those things "breakwaters" myself but was happy for the long-delayed boost in my vocabulary.
In any case, "Boyfriend" was aiko's 6th single and her most successful song to date, going Double Platinum and selling close to 500,000 copies. Written and composed by the singer-songwriter, it peaked at No. 2 on Oricon and became the 54th-ranked song of 2000. The single also became a track on aiko's 3rd album, "Natsu Fuku"（夏服...Summer Clothes）which debuted in June 2001. It hit the top spot on the album charts and became the 23rd-ranked album of the year, also hitting the million barrier.
aiko was born Aiko Yanai（柳井愛子）in 1975. During her elementary school days, she realized that she wanted to go into music as a profession. Strangely enough, her father's friend was the singer Hiroshi Madoka（円広志）, and when she asked him for advice, his straight answer was "It's gonna be tough so don't bother." Luckily, for herself and her future fans, she didn't give up at all and she participated in a high school band and ended up studying at the Osaka Junior College of Music after which she had a stint as a radio DJ at FM Osaka in 1996. Some months later, she participated in "The 5th Music Quest Japan Final" and shared a prize with Ringo Shiina（椎名林檎）which prompted a friendship that has continued to the current day. Almost a couple of years later, aiko released her debut with a major label, "Ashita"（あした...Tomorrow）.
Returning back to where I started, "tetrapod" also became a bit of a burr for aiko herself, albeit briefly. NHK, when aiko was invited to the Kohaku Utagassen in 2000, apparently had some consternation about that particular word in the lyrics since it represented a commercial product. However, as it would turn out, the official lyric had originally been spelled and pronounced as "tetrapot" in the first place, thus negating any potential awkwardness about asking the singer to change the word. It makes me wonder if aiko had sagely predicted this situation months earlier and made that one-letter change. In any case, her appearance on the 2000 special would herald 11 more appearances on the Kohaku, including last year's show.
Ironically, one of my last stints as an English teacher in Tokyo was at a Shinjuku company which produced and sold....tetrapods.