I want something with an older female, if possible I want her to have a cold or serious personality, but it's not necessary. Does anyone have any recommendations?

In shoujo, it's very hard to find a serious heroine. Most of them are noisy or stereotypical.
Also, how much older than the hero you want the heroine to be? Shoujo doesn't offer a big age gap, but Josei and Seinen do.

In shoujo, perhaps the closest titles to that description are Boku no Kotori-san (2 Chapters - Complete), and Hatsukoi Hajimemashita.. The heorine is serious in both and older than the hero. However, I have only seen the later scanlated to Spanish.

Anyway, here are another enjoyable mangas I can suggest you (most of them are ongoing stories since I've tried to suggest you something fresh and new):

Shoujo:

Soba ni Ite mo Ii n Daze: (This is another one close to the type of heroine you want). Still unable to move on from her crush, Lisa had accepted his request her to take care of a certain brat. The brat in question, Kaede is suprisingly great with housework and especially cooking. Despite of their differences the two seems to get along well. Why is it that Kaede is homeless in the first place? Will Lisa be able to confess to her longtime crush? (From MU summary).
Status: 1 scanlated chapter - 1 Volume (Complete)

Zettai ni Tokimeite wa Ikenai!: Heroine (nice personality, not firm nor serious) gets a younger stepbrother (not blood related and they both are in the same grade). Hero takes care of the heroine many times (there's no cold involved, though). It's very cute and like a modern Marmalade Boy (but better I'd say). It's, maybe, the best suited manga for you of the whole list I've made.
Status: 5 scanlated chapters (Ongoing)

Mikansei Lovers: Determined heroine Kotono gets confessed by a short kouhai.
Status: 3 scanlated chapters - 3 Volumes (Complete)

Sunrise!: Takamachi Moka has been away from school due to a lung illness for so long, she has to repeat a grade. Stuck in the first year while her friends move on in the second year she eats lunch alone until a boy with a cat falls down next to her? (From Senpai Scans)
Status: 3 scanlated chapters (Complete).

Taro-kun wa Kou Miete Igai to xxx Desu.: Taro-kun looks scary, but he's actually a nice guy who falls for older heroine.
Status: 9 chapters scanlated + extras - 2 Volumes (Complete)

Fat Cinderella!!: Marina have lived the past twenty years enshrouded in fat and negative energy." Marina is a gloomy young woman who has failed every diet she has ever tried and can't make friends, much less a boyfriend. But, one night, she encounters a gorgeous man with a voice as gentle as a beautiful flower, he whispers to her words as sweet as honey: "Why don't you take a chance with me? I'll make your wish come true." Did God take pity on her and send an angel to grant her wish?! Is the man extending this helping hand to our pudgy Cinderella truly an angel? Or is he not what he seems? Strap in for this thrilling rom-com about a hot rich boy and a pessimistic chubby girl!! (From MU summary)
Status: 9 Chapters (Discontinued)

Suteinu ni Honey Toast: Kohai and his older brother falls for prep-student heroine. Heroine is shy.
Status: 3 Volumes (Complete). I have seen this title scanlated to Spanish only, though.

Tsumasakidachi no Alice: Heroine has a firm character and is older than the guys who can be her possible partners.
Status: 1 scanlated chapters (Ongoing)

Boku wa Uchuujin ni Koi o Shita.: Hero falls in love with a Quantum Physics fan.
Status: 1 scanlated chapters - 1 Volume (Complete)

Hokenshitsu no Kageyama-kun: Heroine gets confessed by her vampire kouhai in the school infirmary.
Status: 5 scanlated chapters - 2 Volumes (Ongoing)

Kawaii kara Yurusu: Kouhai falls for messy senpai.
Status: 1 scanlated chapter - 1 Volume (Complete)

Charai Hayama ni Kyun to Kita: Asahina, a member of the library committee is made to supervise her kouhai, Hayama, who is on probation for hooking up with a fellow student. As time passes, they become friends and maybe more...?
Status: 3 scanlated chapters - 2 Volumes (Complete)

Hoshikuzu Gakuen C Course: When her father is laid off and the family is facing tough times, middle-schooler Kousaka Yayoi selflessly offers to give up her dreams of being a high school student to contribute to the household. Fast forward to a few years later, where Yayoi is about to be given a full-time position at her office jobâ??the only problem is that it requires a high school education! What awaits the 21-year-old high schooler at Hoshinomiya Academy? (From Wildflower Scans)
Status: 2 scanlated chapters - 5 Volumes (Complete). You can find more chapters in Spanish.

Konna Watashi o Kawaii, Nante: Heroine has always had a crush on a handsome guy, but never had the guts to confess. Surprisingly, one day, the handsome guy confesses to her.
Status: 3 Volumes (Ongoing) - Have only seen this title scanlated to Spanish.

Haru wa na Nomi no: Shinomiya Towako, 23 years old, single ... and has an unrequited love on Tonomura Makoto that she dated back in their days of high school. Now they both work at the same elementary school (In the same course!) and are good friends. Will there be a day when Makoto will reply Towakos feelings?
Status: 2 Volumes (Ongoing). Same as the previous title: I have seen it scanlated to Spanish, but not English.

Shounen:

Koi to Utatane: Kouhai and his sensei have a cohabitation relationship. He's very in love with her. Sensei has a serious personality in school, but nice when alone with him. You might like this title as well even if it's a shounen.
Status: 5 scanlated chapters - 3 Volumes (Ongoing)

Seinen:

Cigarette & Cherry: Kouhai falls for sexy serious personality senpai. University students.
Status: 2 scanlated chapters + extra - 1 Volume (Ongoing)

Watashi no Shounen (TAKANO Hitomi): Satoko Tawada is an office worker. She's almost 30 years old, but she still hasn't been able to find happiness in her life. Fate brings her with Mashuu Hayami, a beautiful 12-year-old boy whom she finds practicing soccer all by himself in the park. Out of a whim, she decides to help Mashuu with his practice, with her knowledge of soccer at her disposal. As they practice together on an everyday routine, the two eventually develop an emotional bond. When Satoko's ex-boyfriend deceives her, Mashuu gladly comforts her. And when Satoko learns of Mashuu's mostly absent parents, she starts to concern herself with his personal life. The two lonely souls find common ground and develop an emotional bond that transcends their age difference and circumstances. With this newfound bond, new feelings start to sprout within Satoko. Are these feelings that of maternity? Or is it something else? (From MU summary)
Status: 16 scanlated chapters - 4 Volumes (Ongoing)

Josei:
Note: This genre uses to include nudity and smut.

Kiryuu-sensei wa Renai ga Wakaranai.: Kiryuu-san is a shounen magazine editor. She has no boyfriend and desireds one, but she's clueless when it comes about love. One of her kouhai assistants falls for her, as well anime scriptwriter Kitamura.
Status: 6 scanlated chapters - 5 Volumes (Complete)

30-sai, Shojo OL: Hinako, who just turned 30, is a clean freak who's really sensitive about being touched by men. Naturally, she's never been able to have a good relationship, and is still a virgin. But she doesn't want to die a virgin! And so, she gets her co-worker Kai to introduce a man to her in order to graduate from virginity! She takes her own clothes off and tells the man to tie her up so she can't move! "You can do anything to me!" And so, the man starts to fondle her breasts and move his other hand under her skirt! Will she be able to have sex properly?! Don't miss the hard struggle of this 30-year-old virgin! (From Renta!)
Status: Oneshot.

Bambi to Dhole: Yukimi is her real name but everyone calls her Bambi. She is the student discipline committee member who locks students out of the school if they're a minute late, but sneaks cigarette breaks on the roof. Lone wolf (Dhole, Asiatic wild dog) transfer student Tetsu (everyone pronounces it Tooru) Nagasawa hops the fence after she locks it and breaks her cigarette in half when he finds her on the roof, but he's a super nice guy to a mother and baby on the train. Bambi already has a boyfriend but will the wolf steal her heart? (From MU summary)
Status: 5 scanlated volumes (Complete)

Dame na Watashi ni Koishite Kudasai: The unemployed Shibata Michiko is betting everything she has on her romance with a younger man. In order to keep him happy, she deprives herself of the things she wants and buys him expensive clothing and accessories. Since she's flat out broke, she needs to find a job before she starves to death and loses her young love interest. However, Michiko discovers that the boy was never interested in her romantically. Depressed at being dumped and after a series of unsuccessful interviews, she bumps into Kurosawa, an intimidating former boss she used to dislike. (From Dazzling Scans).
Status: 35 scanlated chapters - 10 Volumes (Complete)

S Love: 27, single, a normal office lady. It's not like she's not interested in a relationship, but she doesn't want to get married. In front of this kind of modern woman, Kanako, there's a lost man appeared. Perhaps this is fate...!? No, but that guy is the last one she wants to love! (From Chibi Manga).
Status: 3 scanlated chapters - 2 Volumes (Complete).

Zettai Toudo: As a result of complications with her first love, Minato has remained a virgin even as a working adult. Turning her back on men, she spends her days adoring a hot guy in a game. However, one morning she wakes up to find a guy who looks just like her first love right next to her. Who is this man? Does this mean she will have another chance at love? (From MU summary)
Status: 2 Volumes (Complete). Have seen it in Spanish only.

Toshishita Kareshi wa Kigen-tsuki.: "Will you drown yourself in my love?" Caresses all over my body, oozing wet deep inside... Should I really be doing this with somebody who's just a substitute boyfriend...!? One day, the man whom Yumina thought of as her boyfriend, suddenly tells her that he is going to marry another woman, and Yumina realizes that he had only been treating her as a fuck buddy. She's unable to talk back to him in the moment, but when she complains about it to her best friend at a cafe the next day, Aoyagi, a waiter at the cafe, butts in! He suggests being Yumina's substitute boyfriend until the wedding, in order to get back at her ex. Her body and soul are now at the mercy of the boy, who is friendly and approachable, but rather forceful during sex...
(From Renta!)
Status: Licenced by Renta. 13 Chapters (Complete)

25-sai no Joshikousei: 25 years old, Hana Natori takes Kaho's place as a student since the two of them are practically identical. But as luck would have it, she is recognized by Okito Kanieâ??an old classmate from her days in high schoolâ??who is now a teacher. (Copied from MyAnimeList)
Status: Not scanlated yet. However it has an anime you might enjoy if you like mild nudity.

Omiai Aite wa Oshiego, Tsuyoki na, Mondaiji.
Status: Same as above: not scanlated yet. However it has an anime you might enjoy if you like mild nudity.

There are a lot of more titles, but these are the ones I have read lately. I hope this list helps!
😉

[img]https://i.imgur.com/6MBFpsv.png[/img]
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Thank you so much,I like most of them.

Quote from KurisuYuki

Thank you so much,I like most of them.

You're very welcome.
If I find another title that is close to what you are looking for, I'll let you know.
Have a good read! 😉

[img]https://i.imgur.com/6MBFpsv.png[/img]
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Kimi wa Pet
Josei, it could have been better researched, but the characters are great.

My Boo
Webtoon, and bittersweet complete ending. It's a lot more than a simple romance. But the heroine is older and capable and the story is so so touching.

Edit: I just found this one. It's really simple, but it's a gem. Game Over (MIZUTANI Fuka)