既有今日何必當初

既 = 旡 + 艮 : Mnemonic symbol: the saying 一言既出，驷马难追 means "lit. once said, a team of horses cannot unsay it (idiom); a promise must be kept". Thus, I'll represent this character with a team of four horses.

Joan of Arc made a bet with a team of four horses that she'd be able to chew 20 chewing gums at once. After stuffing ten of them into her mouth she's already chocking, but what has been said cannot be retracted by a team of four horses.

有 = 𠂇 + 月 : Mnemonic symbol: confetti.

In an act of revolution, with a pair of scissors (𠂇) Maud Younger (y) is cutting a paper moon (月) into tiny pieces in the outhouse's living room (ou3). There is (有) only confetti (有) left over.

今 = 亽 + ㇇ : A rip off calendar showing today's date: 今

今 = 亽 + ㇇ : Joan of Arc has changed into half-duck half-human being and lives in a tipi in front of the encampment. With her beak, she shows a rip off calender with the date of Armageddon: today.

日 = 囗 + 一 : Robinson Crusoe (r) is hiding from the sun (日) in an enclosure (囗) full of flutes (一) in the space station's bathroom (Ø4).

何 = 亻 + 可 : Mnemonic symbol (from "carry"): baby sling

何 = 亻 + 可 : In the elevator's kitchen, Rosa Luxemburg picks up the crying baby Hamlet from his bed of nails, puts him in his baby sling and tries to calm him down.

必 = 丿 + 心 : Mnemonic symbol: 忽必烈 [Hū​bì​liè​], Kublai Khan. Certainly (必) Kublai Khan (必) has to keep face, but he cannot hold it any longer. In the space station's bathroom (Ø4), He absolutely has to (必) tell Brunhilde (bi) his love for her strong character and offers her his heart (心). Brunhilde is a bit embarrassed because all she has to offer in return is a banana (丿). Kublai Khan feels like his heart has been crossed out (the 丿 stroke is crossing out 心 in 必).

当 = 小 + 彐 : This character looks like an angry pitbull. 小 forms the eyes and maybe nose, and 彐 are the dangerous teeth.

当 = 小 + 彐 : Don Quixote opposes a dangerous pit bull in front of the anglepod, and he tries to calm him down with a daisy.

初 = 刀 + 衤 : Back in the days when Chantal Chicken first arrived at the space station as the first junior scientist, she tried really hard to make a good first impression and put on a royal ermine coat. Just to be save she hid a cleaver behind her back just in case she wouldn't be received well.