So tender and young,
Fresh young grass, fair to lie on—
Thus it seems to me;
That someone will bind it close
For a pillow—this I think on.

Meaning

That fresh young grass, so tender and fair to lie upon, seems delightful; yet I cannot help but think that someone will bind it for a pillow and rest upon it.

Commentary

49. So Tender and Young

A certain man, seeing the charming appearance of his younger sister, composed this poem.

He likens his sister to fresh young grass.
It expresses the thought that the young woman, with whom he wishes to share a night in her innocence, will become someone’s wife, and that this is painful and regretful.
Though it shows his feelings for his sister quite frankly, in the Heian period marriage between half-siblings was not uncommon. Or even if they shared the same mother, aristocratic siblings did not ordinarily meet in daily life, and he may have felt a fresh attraction to his grown sister as a woman.

Source

Ise Monogatari

Other

A great sacred wand— So you have named me indeed; Though I drift away, Even one borne down the stream At last will find a shallows.
Now at last I know How bitter a thing it is To wait for someone; I should not have stayed away From the place where one would wait.
Like the first young grass, Why are these words so strange to me? So rare and sudden; Without suspicion till now I have thought of nothing at all.
If birds’ eggs were piled, Ten upon ten, layered high— Even were it so, Would one love a person who Does not think of him at all?

So tender and young, Fresh young grass, fair to lie on— Thus it seems to me; That someone will bind it close For a pillow—this I think on.

So tender and young,
Fresh young grass, fair to lie on—
Thus it seems to me;
That someone will bind it close
For a pillow—this I think on.