If you look at the price seals, you will see the Katakana for サクラ クリエット シャープ / SAKURA CREATE SHARP, ie the joint venture with Tombow in 1971 as pioneers of sliding sleeve technology. For Sakura this lasted until the mid to late 1980s, when they changed their branding to SAKURA SLIDE SHARP.
For the CREATE period, there are some very nice models that don’t follow that standard silhouette. And in the SLIDE SHARP period, there is the CUSHION SLIDE SHARP, the various S1000x designs, etc.