sasimi to tenpura wo tabeta ato, sohu ha atatakai otya wo nomimasita.

Here, と links two nouns and means and.

So:

• 刺身と天ぷら = sashimi and tempura

This と is used when you are listing items fairly completely. It sounds like these are the specific things that were eaten.

A softer, non-exhaustive alternative is や, which would feel more like things like sashimi and tempura.

Because 刺身と天ぷら works together as one combined object.

So the structure is:

• 刺身と天ぷら = the thing(s) eaten
• を = marks that whole phrase as the direct object
• 食べた = ate

Japanese often puts one particle after the entire noun phrase, not after each noun inside it.

あと means after.
When it follows a verb, the verb usually shows the action that happened first.

So:

• 食べたあと = after eating / after [someone] ate

The past form 食べた is normal here. In Japanese, verb-past + あと is a common pattern for after doing X.

Compare:

• 食べる前 = before eating
• 食べた後 = after eating

So the tense before あと does not mean the whole sentence is “extra past”; it is just the standard grammar pattern.

Most likely, yes.

Japanese often leaves out subjects when they are understood from context. In this sentence, 祖父は appears in the main clause, so the natural interpretation is that the grandfather is also the person who ate the sashimi and tempura.

So the implied meaning is:

• After eating sashimi and tempura, my grandfather drank warm tea.

That said, Japanese does sometimes allow this kind of omission even when English would want a clearer subject. Context decides.

は marks the topic of the sentence.

So 祖父は means something like:

• as for my grandfather
• my grandfather (as the topic being talked about)

The sentence is telling us what happened with respect to the grandfather.

A learner might expect が, but は is very common when introducing what the sentence is about, especially in ordinary narration.

祖父 and おじいさん can both refer to a grandfather, but they are used differently.

• 祖父（そふ）: your own grandfather, especially in a more neutral or humble way
• おじいさん: grandfather / old man, often used for someone else’s grandfather or when addressing a grandfather directly

In many contexts, when speaking about your own family member to someone else, Japanese prefers the plain family term like 祖父 rather than the more honorific-sounding おじいさん.

Because they are doing different jobs in the sentence.

• 食べた is inside the time expression 食べたあと.
• 飲みました is the main verb of the sentence.

In Japanese, the main verb usually determines the sentence’s politeness level. Subordinate parts like 〜たあと often stay in plain form even in polite sentences.

So this combination is completely normal:

• 食べたあと、…飲みました。

温かい means warm and is commonly used for things that are warm to the touch or pleasant in temperature, including drinks like tea.

Japanese has both:

• 温かい = warm
• 暖かい = warm, usually for weather, air, climate, atmosphere

So for tea, 温かいお茶 is the natural choice.

Japanese usually follows Subject/Topic – Object – Verb, and time expressions often come before the main clause.

This sentence is structured like:

• 刺身と天ぷらを食べたあと = after eating sashimi and tempura
• 祖父は = as for my grandfather
• 温かいお茶を = warm tea
• 飲みました = drank

The verb normally comes at the end of the clause in Japanese. That is one of the biggest differences from English.

They are read:

• 刺身 = さしみ
• 天ぷら = てんぷら
• 祖父 = そふ
• 温かい = あたたかい
• お茶 = おちゃ
• 飲みました = のみました

A common point to notice is that 祖父 is そふ, not そぼ.

Yes. It can be written as 後.

So:

• 食べたあと
• 食べた後

Both are correct. In everyday writing, many learners will see both versions. Using hiragana for あと is very common and often easier to read.

Because 食べたあと already forms a complete time expression: after eating.

It directly connects to the main clause, so you do not need another particle there.

The comma simply helps readability:

• 刺身と天ぷらを食べたあと、祖父は温かいお茶を飲みました。

Without the comma, the sentence would still be grammatical, but the comma makes the pause clearer.