If you're a Japanese man raised by middle class parents, the prospect of working as a cashier or janitor implies:

You will never have economic security. Substantially all cashiers are hourly contract workers; virtually all janitors are. (The janitorial exceptions are government employees.) Contract workers can have their employment terminated in a fashion similar to in the United States. This contrasts markedly with the traditional expectation of the Japanese middle class, which is lifetime employment.

Your parents will consider you a failure, principally because you have failed in the one thing men are expected to do.

You will find your dating and marriage prospects markedly curtailed. You will be considered a loser by the vast majority of young women who you wish to date. Some will tell you that, in as many words. Many will prefer euphemisms like "My ideal boyfriend is someone who has debuted in society." Honest labor as a cashier is not considered honest labor in the Japanese middle class, at least not for a member of the middle class.

Japan is a very status-conscious society. Cashiers and janitors occupy some of the very lowest rungs of it. You will spend most of your day being obseqiously polite to people; you will watch other people spend their fragments of your day snubbing you, repeatedly, in the ordinary course.

You have recently read of other blue-collar employees who worked service jobs dying cold and alone, because the government safety net doesn't really consider them a priority, they had no savings, and they never had a family for the above reasons.

So, tell me: given that this is your mental model of reality, and the mental model shared by substantially everyone you consider a peer or mentor, how attractive does working at 7-11 sound to you?

Oh, salient fact: if you work so much as one day at 7-11 past college you'll probably never work as a salaryman. You're damaged goods for the rest of your life. If you thought of maybe doing it for 6 months while spending your time playing in a band and then getting on with your adult life, go ask one of the 45 year olds working at 7-11 and living on ~$1,400 a month how that decision worked out for them.

The above math, or something close to it, is why most salarymen consider themselves blessed to be proper employees at a stable corporation, even if that job is actively killing them. (n.b. I'm not Japanese but I am a recovering Japanese salaryman. "Salaryman" is a local coinage which identifies full-time white collar employees of a certain strata of Japanese companies which are desirable to work at. The traditional expectation is that you sign a deal with the devil ^H^H^H^H^H your company where the company insulates you from all risks and in return you commit to the company mind, body, and soul.)