tamatama ane mo tikaku de heya wo sagasite ita node, issyo ni mi ni ikimasita.

たまたま means by chance, coincidentally, or it just so happened that.

In this sentence, it modifies the whole first part:

• たまたま姉も近くで部屋を探していたので
• Since my older sister also happened to be looking for a room nearby...

It gives the idea that this was not planned.

も means also or too.

So 姉も means my older sister too. It implies that someone else was also looking for a room — most likely the speaker.

A useful point:

• も often replaces は or が
• so instead of saying 姉が, the sentence says 姉も to add the meaning of too

Yes. In Japanese, family words like 姉, 母, 父, 兄 often mean my family member when the context is clear.

So:

• 姉 = my older sister
• 私の姉 is possible, but often unnecessary

Japanese often leaves out things that are already understood from context.

近く means nearby or the nearby area.

With で, it becomes the place where the action happens:

• 近くで部屋を探す
• to look for a room nearby

Here, で marks the location of the activity 探す.

Compare:

• 近くで探す = search in the nearby area
• 近くにある = exist/be located nearby

So で is used because this is an action taking place in that area.

探していた is the past form of 探している.

Here it means was looking for or had been looking for. It shows an ongoing action or situation in the past.

So:

• 探した = looked for / searched for
• 探していた = was looking for / had been looking for

In this sentence, 探していた sounds natural because the sister was in the middle of room-hunting around that time.

ので means because or since.

It connects the reason to the result:

• 姉も近くで部屋を探していたので
• because my older sister was also looking for a room nearby

Then the result:

• 一緒に見に行きました
• we went to see it together

Compared with から, ので usually sounds a bit softer and more explanatory.

This is completely normal.

Before ので, Japanese uses the plain form:

• 探していたので

But the main sentence can still be polite:

• 行きました

So the structure is:

• plain form + ので
• polite main clause

This is a very common pattern in everyday Japanese.

一緒に means together.

It tells you that the speaker and the older sister did the next action together:

• 一緒に見に行きました
• went to see it together

Japanese often does not repeat exactly with whom if it is already obvious from the previous clause.

This is a very common pattern:

• verb stem + に + 行く

It means go in order to do something.

Here:

• 見ます → stem 見
• 見に行く = go to see
• 見に行きました = went to see

So:

• 部屋を見に行く = go to look at a room

This pattern is used with many verbs:

• 食べに行く = go to eat
• 買いに行く = go to buy
• 会いに行く = go to meet

The thing being seen is understood to be the room or rooms being discussed.

Japanese often leaves out repeated objects when they are obvious from context. Since the sentence already mentioned 部屋を探していた, it is natural not to repeat 部屋を again.

So the full idea is something like:

• we went together to look at a room / some rooms

The subject is omitted, which is very normal in Japanese.

From context, it is most naturally understood as:

• the speaker, and probably the older sister too

Because of 一緒に, the meaning is that they went together.

Japanese often leaves out subjects when they are clear from the situation, especially I, we, or people already mentioned.

It usually suggests a continuing situation.

探していた does not just mean one single moment of searching. It often means the person was in the state of looking for a room during that period.

So the nuance is closer to:

• she was looking for a room nearby
• she had been room-hunting nearby

This is why it fits well with the idea that they then went together to view one.