I asked a German Ph.D student, who was my supervisor, to let me know what do you feelhe thinks is weird in Tokyo. I asked a German Ph.D student, who was my supervisor, to let me know what he thinks is weird in Tokyo.

This sentence is unclear about the timing of your story. "Was my supervisor" makes it sound like it happen a long time ago. If so you might want to say "A long time ago, I ...". If not, another reference to time would be useful. "I asked a German Ph.D. student, who was my supervisor last year/today/at the time,..."

I asked German Ph.D student, who was my supervisor, to let me know what do you feeltell me what he found weird inabout Tokyo. I asked German Ph.D student, who was my supervisor, to tell me what he found weird about Tokyo.

I'm not sure whether you really mean 'weird'. I don't think either of your supervisor's examples is particularly weird. Unusual, but not weird. But maybe that is what you mean.

First, there is a mixed area noted the mix of historical architectures, shrines, temples, and modern buildings within the same area. First, he noted the mix of historical architectures, shrines, temples, and modern buildings within the same area.

It sounds more natural to describe what he said instead of just listing them.

First, there is a mixed area of historical architectures, shrines, temples, and modern buildings. First, there is a mixed area of historical architecture, shrines, temples, and modern buildings.

This sounds pretty good if you are talking about just one area where this occurs. If you mean that Tokyo as a whole has a mixture of historical ... -- then you could put it the way I did here. Architecture is always singular.

I'm going to post about it later if I don't forget it. I'm going to post about it later if I don't forget.

I'm going to post about it later if I don't forget it. I'm going to post about it later if I don't forget.

The second is that an old security guard, who looked to have nothing to do andexcept for greeteding him meaninglessly every day in front of the building (a temporary accommodation that the university provides) meaninglessly. The second is that an old security guard, who looked to have nothing to do except for greeting him meaninglessly every day in front of the building (a temporary accommodation that the university provides).

It's not clear to me what "greeted meaninglessly" means. You could leave it out, or use more detail to describe what the guard was doing. edit: added some more corrections to this sentence

The second is that the old security guard lookseemed to have nothing to do and greeted him in front of the building (temporary accommodation the university provides) meaninglessly. The second is that the old security guard seemed to have nothing to do and greeted him in front of the building (temporary accommodation the university provides) meaninglessly.

I'm not sure what you mean -- greet someone meaninglessly. If you mean it was with polite words and no real interest, then that's the correct word. But there is nothing weird about that. It's what you would expect from a security guard.

He wonder ifed why the majority of security guards and taxi drivers are gray old men who seemed to be close to retirement age. He wondered why the majority of security guards and taxi drivers are gray old men who seemed to be close to retirement age.

He wonder ifed why the majority of security guards and taxi drivers are gray old men who seemed to be close to retirement age. He wondered why the majority of security guards and taxi drivers are gray old men who seem to be close to retirement age.

I haven't ever deemed such scenes to be weird. I haven't ever deemed such scenes to be weird.

I havedn't ever deemconsidered such scene to be weird. I hadn't ever considered such scene to be weird.

'Deemed' is an appropriate word but it would normally be used in formal writing.

If they were attacked by terrorists (Are there any good phrase? ), how do they protect hithemselfves without any weapons.? If they were attacked by terrorists (Are there any good phrase? ), how do they protect themselves without any weapons?

There isn't a general phrase for that, it sounds fine.

If they were attacked by terrorist (Are there any good phrase? )s, how wouldo they protect hithemselfves without any weapons.? If they were attacked by terrorists, how would they protect themselves without weapons?

Terrorists seem like a very unlikely event. Do you mean something milder, e.g. if they were threatened?