watasi ha tukue no ue ni thissyu wo oite, doraiyaa ha senmenzyo ni simaimasu.

は marks the topic of the sentence. Here, 私は sets the frame as as for me or speaking of me.

In natural English, we usually just say I, so this distinction is easy to miss. Japanese often separates:

• the topic with は
• the direct object with を
• locations and destinations with particles like に

Also, in real conversation, 私 would often be omitted if it is already obvious who is acting.

を marks the direct object of the verb.

In ティッシュを置いて, the thing being placed is ティッシュ, so it takes を.

So the structure is:

• ティッシュ = the thing
• を = marks it as the object
• 置いて = put/place

Here, の connects two nouns.

机の上 literally means the desk’s top or the top of the desk, which in natural English is on the desk.

So:

• 机 = desk
• 上 = top / above / surface
• 机の上 = the top/surface of the desk

This use of の is not just possession. It often means of, on, belonging to, or related to, depending on context.

With verbs like 置く and しまう, に marks the place where something is put or ends up.

So:

• 机の上に置く = put something on the desk
• 洗面所にしまう = put something away in the washroom

A useful way to think about it is:

• に often marks a destination or resulting location
• で often marks the place where an action happens

Here, the important idea is where the item is placed, so に is the natural choice.

置いて is the て-form of 置く.

The て-form is being used to connect this verb to the next one:

• ティッシュを置いて、ドライヤーは洗面所にしまいます。

So it means something like:

• put the tissues on the desk, and then put away the hair dryer in the washroom
• or more simply, put the tissues on the desk and put away the hair dryer in the washroom

The て-form is very commonly used to link actions in Japanese.

When Japanese connects verbs in one sentence, the earlier verb usually appears in て-form, and only the final verb carries the full tense and politeness marking.

So this is normal:

• 置いて、しまいます

Instead of:

• 置きます、しまいます ← not correct for this kind of connection

The politeness of the whole sentence is shown at the end by しまいます. The first verb does not need its own polite ending here.

Here, しまいます means put away, store, or put back in its proper place.

This is important because learners often confuse it with the grammar pattern 〜てしまう, which means something like finish doing or do completely/regrettably.

But in this sentence, しまいます is its own main verb:

• ドライヤーは洗面所にしまいます
• As for the hair dryer, I put it away in the washroom.

So this is not:

• 置いてしまいます It is:
• 置いて、しまいます

Two separate actions, with two separate verbs.

This は gives a contrastive feeling.

The sentence is setting up two different items and saying what happens to each:

• ティッシュ goes on the desk
• ドライヤー goes in the washroom

So ドライヤーは can feel like:

• as for the hair dryer
• the hair dryer, on the other hand, ...

If the sentence said ドライヤーを洗面所にしまいます, that would be more neutral and straightforward: I put away the hair dryer in the washroom.

Using は makes the contrast between the two items more noticeable.

Yes. The doer is still understood to be 私.

Japanese often omits repeated subjects once they are clear. So after 私は at the start, the listener normally understands that the same person continues doing the later actions unless something indicates otherwise.

So the sentence is understood as:

• I put the tissues on the desk, and I put away the hair dryer in the washroom.

Even though 私 is not repeated, it is still implied.

Japanese nouns usually do not mark singular/plural the way English does, and they also do not use articles like a, an, or the.

So ティッシュ could mean:

• a tissue
• tissues
• sometimes even a box of tissues

The exact English translation depends on context.

This is very common in Japanese: the noun itself stays the same, and the listener figures out the number from the situation.

Grammatically, no. It can be omitted if the subject is already obvious.

A very natural version would often be:

• 机の上にティッシュを置いて、ドライヤーは洗面所にしまいます。

Or, if the speaker wants to contrast both items:

• ティッシュは机の上に置いて、ドライヤーは洗面所にしまいます。

Japanese regularly leaves out pronouns when they are understood from context, much more often than English does.