[Spoilers] Help understanding the last riddle for True End

[Mustard Panda]

I got to the end of the game but I couldn't for the life of me figure out what I was supposed to type in the Teacher's diary. I found the riddle beside it but I had no idea what to do with it. In the end I used a guide to look up the answer. I tried following the hint (it's sounding out his name) and I was thinking about what the teacher said about how he doesn't like his name and hopes he can live up to it. No dice.

So can someone please explain how you get David out of the riddle beside his diary? I will never figure this out on my own lol.

Also was he referring to David as in David and Goliath when he said he hopes he can live up to his name?

[cheru]

So for the riddle you have
"I'm in drink, but not in rink." as the first line
This tells you that the letter you are looking for is in the word "drink" but isn't in the word "rink"
When you look at the two words, you will see an overlap in the letters. If you remove all the overlapped letters you get D R I N K, leaving you with only D. This gives you the first letter. And then you repeat the process with the rest of the lines.
Does that make more sense?

[slothmama]

Haha... yeah, I remember the riddle is more harder in English than it is in Japanese ^q^ ;;

Also, here's spoiler territory after this sentence but he was referring to the meaning of the name David: Beloved. Or in the game's terms; 'Recipient of Love'.

He's never known love and has never felt that he was a person that was ever deserving of being loved in his life no matter how much he wished for it otherwise. It's why Fiona complains about how blind he is to all the people around him that love and cherish him.

Though the idea of him being based off of David and Goliath (like how all the kids are based off of fairy tales) is certainly interesting and could possibly be interpreted as such depending on what exactly the Goliath is supposed to represent in this case. Though probably not since while I enjoy miwashiba's works, they're usually Not That Deep