Visa'free transit 144 hours

You are correct when you have concluded that your second itinerary is eligible for 144 hour visa free transit. The first one is not because this is considered to be a return trip "Tokyo - Shanghai - Tokyo" and this type of itinerary is not eligible.

I am afraid I did not properly understood your question regarding a person with Spanish citizenship. Do you mean if a Spanish citizen is flying that same itinerary does she/he need a visa? The answer is no if the itinerary is eligible like one you have presented "Seoul - Shanghai - Tokyo".

However, Spanish and all EU passport holders need a visa for China if they want to travel outside of this 144 hour visa free transit scheme.

Thank you so much for your reply! Borut:What I meant if I have a flight that has a stop over on my way to China 🇨🇳 for example Mexico—- Tokyo (stop over) — Shanghai—- Tokyo (we want to travel there) is that possible to apply for the 144 hours visa free transit ? Or that stop over counts as we were there.
Thank you again :)

The stopover will be counted as a destination so this is not eligible for the 144-hour visa-free transit. You need to obtain a Chinese visa in advance.

Indeed, it is important to have in mind that the only detail that is of essential importance is the fact that only the immediate points before and after your Chinese destination matter and those immediate points have to be in two different countries or eligible Chinese territories (eligible Chinese territories are Hong Kong, Taiwan and Macau).