You cannot collect or use an individual's email address for marketing purposes without their explicit, prior consent.
Most Japanese corporate websites have a 問い合わせ (Inquiry) page. While it’s slower, sending a personalized message through an official form is often more effective than hitting a generic Gmail inbox that might not be monitored. Tips for Outreach in Japan
High hard-bounce rates (undeliverable emails) signal to ESPs that you are a spammer.