* Specific Brand/Model: If you mean a specific brand of ball that was popular in a certain era (e.g., a particular model of Mitre, Adidas, or other brand from the 70s, 80s, or 90s), your best bet is to search online marketplaces like eBay, Etsy, or specialized vintage sports equipment sites. Use specific keywords like the brand name and the era ("Adidas Myachi 1980s"). Be prepared to pay a premium for a genuine vintage ball in good condition.
* Style/Appearance: If you mean a ball that *looks* like a classic Myachi-style ball (perhaps a certain color, panel design, or material), you might have more options. Many modern manufacturers produce balls that evoke a retro aesthetic. Look for balls described as "retro," "vintage-inspired," or with similar terminology. You might find these on sporting goods websites or in sporting goods stores.
* "Myachi" as a general term: If "Myachi" is just a general term you're using to refer to a type of football, then clarifying the style you are looking for (e.g., leather, specific panel pattern) will help you find suitable options. Search for footballs that match that description.
In short, your search strategy needs to be more specific. The more details you provide about the particular "Old School Myachi" you want (brand, year, color, features), the better your chances of finding one.